Issue 16944: Weekday definitions are inadequate (date-time-ftf) Source: NIST (Mr. Edward J. Barkmeyer, edbark(at)nist.gov) Nature: Uncategorized Issue Severity: Summary: The definitions of the weekdays in 9.5.6 simply identify them as 'day of week' time points. ('day of week' is erroneously represented as a name instead of a noun concept) What is being defined in the textDTV is apparently the individual time point, but the UML diagram shows that each day of week time point is in fact a general concept (that corresponds to time intervals). The text should make this clear. Further, the delimiting property for each of these concepts is specified in a Necessity that is intended to be taken as part of the definition: e.g., Each Tuesday is met by a Monday. That is, the intended definition of the general concept 'Tuesday' is: time interval that is an instance of a calendar day and that is met by an instance of Monday. The definition of the individual concept "Tuesday" is: the time point that has index 2 in the week of days scale, and that is the concept 'Tuesday'. Somehow the text has to make these two definitions clear. It takes significant effort for the reader to understand that the individual 'Tuesday the time point' can have instances, so that "each Tuesday" makes sense. It may be sufficient to phrase the Necessity as: Each instance of (time point) Tuesday is met by an instance of (time point) Monday. (SBVR Annex C provides a notation [Tuesday] to refer to the concept as a thing, and CLIF has no problem with the designation (symbol+concept) playing both predicate and argument roles.) Finally, the following Necessity should appear under 'calendar day' in 9.5.3: For each calendar, each instance of a 'calendar day' that is defined by the calendar is met by at most one instance of a calendar day that is defined by the calendar. Otherwise, the ontology could technically permit a day to be both a Tuesday and a Friday. It may be that this follows from the necessities for the relationships of the time scales to the Time Axis. If so, the Necessity is not needed, but a Note should mention the sequencing rules. Resolution: Revised Text: Actions taken: January 5, 2012: received issue Discussion: End of Annotations:===== te: Thu, 05 Jan 2012 18:41:00 -0500 From: Ed Barkmeyer Reply-To: edbark@nist.gov Organization: NIST User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) To: issues@omg.org Subject: DTV Issue: Weekday definitions are inadequate X-NISTMEL-MailScanner-Information: Please contact postmaster@mel.nist.gov for more information X-NISTMEL-MailScanner-ID: q05Nf5EI028194 X-NISTMEL-MailScanner: Found to be clean X-NISTMEL-MailScanner-SpamCheck: X-NISTMEL-MailScanner-From: edbark@nist.gov X-NISTMEL-MailScanner-Watermark: 1326411666.89027@7xT1jXxEVXWcq/USJpjoEQ X-Spam-Status: No X-NIST-MailScanner: Found to be clean X-NIST-MailScanner-From: edbark@nist.gov Specification: Date Time Vocabulary Version: beta-1 Title: Weekday definitions are inadequate Source: Ed Barkmeyer, NIST, edbark@nist.gov Summary: The definitions of the weekdays in 9.5.6 simply identify them as 'day of week' time points. ('day of week' is erroneously represented as a name instead of a noun concept) What is being defined in the textDTV is apparently the individual time point, but the UML diagram shows that each day of week time point is in fact a general concept (that corresponds to time intervals). The text should make this clear. Further, the delimiting property for each of these concepts is specified in a Necessity that is intended to be taken as part of the definition: e.g., Each Tuesday is met by a Monday. That is, the intended definition of the general concept 'Tuesday' is: time interval that is an instance of a calendar day and that is met by an instance of Monday. The definition of the individual concept "Tuesday" is: the time point that has index 2 in the week of days scale, and that is the concept 'Tuesday'. Somehow the text has to make these two definitions clear. It takes significant effort for the reader to understand that the individual 'Tuesday the time point' can have instances, so that "each Tuesday" makes sense. It may be sufficient to phrase the Necessity as: Each instance of (time point) Tuesday is met by an instance of (time point) Monday. (SBVR Annex C provides a notation [Tuesday] to refer to the concept as a thing, and CLIF has no problem with the designation (symbol+concept) playing both predicate and argument roles.) Finally, the following Necessity should appear under 'calendar day' in 9.5.3: For each calendar, each instance of a 'calendar day' that is defined by the calendar is met by at most one instance of a calendar day that is defined by the calendar. Otherwise, the ontology could technically permit a day to be both a Tuesday and a Friday. It may be that this follows from the necessities for the relationships of the time scales to the Time Axis. If so, the Necessity is not needed, but a Note should mention the sequencing rules. -- Edward J. Barkmeyer Email: edbark@nist.gov National Institute of Standards & Technology Manufacturing Systems Integration Division 100 Bureau Drive, Stop 8263 Tel: +1 301-975-3528 Gaithersburg, MD 20899-8263 Cel: +1 240-672-5800 Date: Fri, 15 Jun 2012 17:03:13 -0400 From: Ed Barkmeyer Reply-To: Organization: NIST User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) To: OMG DateTimeVoc FTF Subject: Re: DTV issue 16944 - Weekday definitions are inadequate X-NISTMEL-MailScanner-Information: Please contact postmaster@mel.nist.gov for more information X-NISTMEL-MailScanner-ID: q5FL3KYg020845 X-NISTMEL-MailScanner: Found to be clean X-NISTMEL-MailScanner-SpamCheck: X-NISTMEL-MailScanner-From: edbark@nist.gov X-NISTMEL-MailScanner-Watermark: 1340399002.25831@snAdDpFHHSp+Av1tEJhZzw X-Spam-Status: No At one of the DTV telecons, I was asked to produce a proposed "pattern" for the resolution of this issue. I attach a draft resolution that demonstrates a proposed pattern. It includes other elements to be discussed. -Ed -- Edward J. Barkmeyer Email: edbark@nist.gov National Institute of Standards & Technology Manufacturing Systems Integration Division 100 Bureau Drive, Stop 8263 Tel: +1 301-975-3528 Gaithersburg, MD 20899-8263 Cel: +1 240-672-5800 Issue 16944-d1.docx Date: Wed, 3 Oct 2012 17:48:49 -0400 From: Ed Barkmeyer Reply-To: Organization: NIST User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) To: OMG DateTimeVoc FTF Subject: DTV Issue 16944 draft resolution -- definitions of months and weekdays (named time points) X-NISTMEL-MailScanner-Information: Please contact postmaster@mel.nist.gov for more information X-NISTMEL-MailScanner-ID: q93Lmtsp006135 X-NISTMEL-MailScanner: Found to be clean X-NISTMEL-MailScanner-SpamCheck: X-NISTMEL-MailScanner-From: edbark@nist.gov X-NISTMEL-MailScanner-Watermark: 1349905736.8248@sHxbGRA9cSHt6682e++unQ X-Spam-Status: No All, The original of this draft, showing just the intended pattern, was distributed on 15 June. Hearing no objections, I have written up the full version. The proposed changes reorganize and correct the wording of the definitions and necessities for the named time points, like January and Tuesday. If someone wants a change to the pattern, speak now, before it goes to ballot. There is an issue in the writeup. It introduces the concept 'calendar day period' -- a time interval that some calendar day time point corresponds to -- just to shorten some of the definitions. It is not clear whether the concept is generally useful, and without it the definitions just grow a second characteristic: "and that has a duration that is one day". Is it worth adding this concept, or should we just remove those changes? Also, if anyone notes other errors in the writeup, please mention them. Thanks, -Ed -- Edward J. Barkmeyer Email: edbark@nist.gov National Institute of Standards & Technology Systems Integration Division, Engineering Laboratory 100 Bureau Drive, Stop 8263 Tel: +1 301-975-3528 Gaithersburg, MD 20899-8263 Cel: +1 240-672-5800 "The opinions expressed above do not reflect consensus of NIST, and have not been reviewed by any Government authority." DTV Issue 16944-weekday definitions-d2.docx Disposition: Resolved OMG Issue No: 16944 Title: Weekday definitions are inadequate Source: Ed Barkmeyer, NIST, edbark@nist.gov Summary: The definitions of the weekdays in 9.5.6 simply identify them as 'day of week' time points. ('day of week' is erroneously represented as a name instead of a noun concept) What is being defined in the text is apparently the individual time point, but the UML diagram shows that each day of week time point is in fact a general concept (that corresponds to time intervals). The text should make this clear. Further, the delimiting property for each of these concepts is specified in a Necessity that is intended to be taken as part of the definition: e.g., Each Tuesday is met by a Monday. That is, the intended definition of the general concept 'Tuesday' is: time interval that is an instance of a calendar day and that is met by an instance of Monday. The definition of the individual concept "Tuesday" is: the time point that has index 2 in the week of days scale, and that is the concept 'Tuesday'. Somehow the text has to make these two definitions clear. It takes significant effort for the reader to understand that the individual 'Tuesday the time point' can have instances, so that "each Tuesday" makes sense. It may be sufficient to phrase the Necessity as: Each instance of (time point) Tuesday is met by an instance of (time point) Monday. (SBVR Annex C provides a notation [Tuesday] to refer to the concept as a thing, and CLIF has no problem with the designation (symbol+concept) playing both predicate and argument roles.) Finally, the following Necessity should appear under 'calendar day' in 9.5.3: For each calendar, each instance of a 'calendar day' that is defined by the calendar is met by at most one instance of a calendar day that is defined by the calendar. Otherwise, the ontology could technically permit a day to be both a Tuesday and a Friday. It may be that this follows from the necessities for the relationships of the time scales to the Time Axis. If so, the Necessity is not needed, but a Note should mention the sequencing rules. Resolution: The last element above, the missing axiom, is added to clause 10.2. The FTF agrees that the Necessities in 12.3 (was 9.5.6) do not follow from the definitions, and they are not quite accurate as concept definitions: For example, a time interval is a Tuesday if and only if it is a Gregorian calendar day and is met by a Monday. The current definitions just state facts about the concepts. So the text is revised to define the time points as concepts and state their positions in the time scale as Necessities. This problem was found to apply to the definitions of Gregorian months in 11.3 (was 9.5.5) as well, and this resolution corrects those definitions similarly. In order to simplify the definition expressions, an abstract concept .calendar day period. is introduced. Revised Text: 1. In clause 10.2, in the entry for .calendar day., after the Definition, ADD: Necessity: For each calendar, each instance of a calendar day that is defined by the calendar is met by at most one instance of a calendar day that is defined by the calendar. 2. In clause 10.2, after the entry for .day period., INSERT a new entry: calendar day period Definition: day period that is an instance of a calendar day Note: A calendar day period is a day period that is from midnight to midnight. 3. In clause 10.2 add calendar day period to the UML model need UML diagram 10.2bis 4. In clause 11.3, change the styling for .January., .February., .March., .April., .May., .June., .July., .August., .September., .October., .November., and .December. from .name. (double underscore) to .term. (single underscore) in all occurrences. 5. In clause 11.3, in the entry for January, REPLACE the Definition and the first four Necessity paragraphs: Definition: Gregorian month of year in sequence position 1 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each January is met by the last Gregorian day of month of a December. Necessity: Each January starts a Gregorian year. Necessity: January has 31 Gregorian days of month. Necessity: The duration of each January is 31 days. with: Definition: time interval that has duration 31 days and that starts an instance of a Gregorian year Necessity: The concept .January. is the Gregorian month of year that is in sequence position 1 of the Gregorian year-of-months scale. Necessity: The time point .January. has 31 Gregorian days of month. Necessity: Each January is met by a December. 6. In clause 11.3, in the entry for February, REPLACE the Definition and the first five Necessity paragraphs: Definition: Gregorian month of year in sequence position 2 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each February is met by the last Gregorian day of month of a January. Necessity: If the Gregorian year is a leap year, then February has 29 Gregorian days of month. Necessity: If the Gregorian year is a common year, then February has 28 Gregorian days of month. Necessity: The duration of each February that is of a leap year is 29 days. Necessity: The duration of each February that is of a common year is 28 days. with: Definition: time interval that is met by a January and that has a duration that is 28 days if the time interval is part of an instance of a common year, or that is 29 days if the time interval is part of an instance of a leap year Necessity: The concept .February. is the Gregorian month of year that is in sequence position 2 of the Gregorian year-of-months scale. Necessity: The time point .February. has 29 Gregorian days of month. 7. In clause 11.3, in the entry for March, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 3 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each March is met by the last Gregorian day of month of a February. Necessity: March has 31 Gregorian days of month. Necessity: The duration of each March is 31 days. with: Definition: time interval that is met by a February and that has a duration that is 31 days Necessity: The concept .March. is the Gregorian month of year that is in sequence position 3 of the Gregorian year-of-months scale. Necessity: The time point .March. has 31 Gregorian days of month. 8. In clause 11.3, in the entry for April, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 4 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each April is met by the last Gregorian day of month of a March. Necessity: April has 30 Gregorian days of month. Necessity: The duration of each April is 30 days. with: Definition: time interval that is met by a March and that has a duration that is 30 days Necessity: The concept .April. is the Gregorian month of year that is in sequence position 4 of the Gregorian year-of-months scale. Necessity: The time point .April. has 30 Gregorian days of month. 9. In clause 11.3, in the entry for May, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 5 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each May is met by the last Gregorian day of month of an April. Necessity: May has 31 Gregorian days of month. Necessity: The duration of each May is 31 days. with: Definition: time interval that is met by an April and that has a duration that is 31 days Necessity: The concept .May. is the Gregorian month of year that is in sequence position 5 of the Gregorian year-of-months scale. Necessity: The time point .May. has 31 Gregorian days of month. 10. In clause 11.3, in the entry for June, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 6 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each June is met by the last Gregorian day of month of a May. Necessity: June has 30 Gregorian days of month. Necessity: The duration of each June is 30 days. with: Definition: time interval that is met by a May and that has a duration that is 30 days Necessity: The concept .June. is the Gregorian month of year that is in sequence position 6 of the Gregorian year-of-months scale. Necessity: The time point .June. has 30 Gregorian days of month. 11. In clause 11.3, in the entry for July, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 7 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each July is met by the last Gregorian day of month of a June. Necessity: July has 31 Gregorian days of month. Necessity: The duration of each July is 31 days. with: Definition: time interval that is met by a June and that has a duration that is 31 days Necessity: The concept .July. is the Gregorian month of year that is in sequence position 7 of the Gregorian year-of-months scale. Necessity: The time point .July. has 31 Gregorian days of month. 12. In clause 11.3, in the entry for August, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 8 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each August is met by the last Gregorian day of month of a July. Necessity: August has 31 Gregorian days of month. Necessity: The duration of each August is 31 days. with: Definition: time interval that is met by a July and that has a duration that is 31 days Necessity: The concept .August. is the Gregorian month of year that is in sequence position 8 of the Gregorian year-of-months scale. Necessity: The time point .August. has 31 Gregorian days of month. 13. In clause 11.3, in the entry for September, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 9 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each September is met by the last Gregorian day of month of an August. Necessity: September has 30 Gregorian days of month. Necessity: The duration of each September is 30 days. with: Definition: time interval that is met by an August and that has a duration that is 30 days Necessity: The concept .September. is the Gregorian month of year that is in sequence position 9 of the Gregorian year-of-months scale. Necessity: The time point .September. has 30 Gregorian days of month. 14. In clause 11.3, in the entry for October, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 10 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each October is met by the last Gregorian day of month of a September. Necessity: October has 31 Gregorian days of month. Necessity: The duration of each October is 31 days. with: Definition: time interval that is met by a September and that has a duration that is 31 days Necessity: The concept .October. is the Gregorian month of year that is in sequence position 10 of the Gregorian year-of-months scale. Necessity: The time point .October. has 31 Gregorian days of month. 15. In clause 11.3, in the entry for November, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 11 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each November is met by the last Gregorian day of month of an October. Necessity: November has 30 Gregorian days of month. Necessity: The duration of each November is 30 days. with: Definition: time interval that is met by an October and that has a duration that is 30 days Necessity: The concept .November. is the Gregorian month of year that is in sequence position 11 of the Gregorian year-of-months scale. Necessity: The time point .November. has 30 Gregorian days of month. 16. In clause 11.3, in the entry for December, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 12 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each December is met by the last Gregorian day of month of a November. Necessity: December has 31 Gregorian days of month. Necessity: The duration of each December is 31 days. with: Definition: time interval that is met by a November and that has a duration that is 31 days Necessity: The concept .December. is the Gregorian month of year that is in sequence position 12 of the Gregorian year-of-months scale. Necessity: The time point .December. has 31 Gregorian days of month. Necessity: Each December finishes an instance of a Gregorian year. 17. In clause 12.3, change the styling for .Monday., .Tuesday., .Wednesday., .Thursday., .Friday., .Saturday. and .Sunday. from .name. (double underscore) to .term. (single underscore) in all occurrences. 18. In clause 12.3, REPLACE Figure 12.2 with: in the UML model, make all the time points subtypes of calendar day period instead of time period. 19. In clause 12.3, in the entry for .day of week., after the first Note, INSERT a new Note: Note: Each day of week time point is a concept that corresponds to time intervals that are calendar day periods. 20. In clause 12.3, in the entry for Monday, REPLACE the Definition and the Necessity: Definition: day of week in sequence position 1 of the week of days scale Necessity: Each Monday is met by a Sunday. with: Definition: calendar day period that starts an instance of a calendar week Necessity: The concept .Monday. is the day of week that is in sequence position 1 of the week of days scale. 21. In clause 12.3, in the entry for Tuesday, REPLACE the Definition and the Necessity: Definition: day of week in sequence position 2 of the week of days scale Necessity: Each Tuesday is met by a Monday. with: Definition: calendar day period that is met by a Monday Necessity: The concept .Tuesday. is the day of week that is in sequence position 2 of the week of days scale. 22. In clause 12.3, in the entry for Wednesday, REPLACE the Definition and the Necessity: Definition: day of week in sequence position 3 of the week of days scale Necessity: Each Wednesday is met by a Tuesday. with: Definition: calendar day period that is met by a Tuesday Necessity: The concept .Wednesday. is the day of week that is in sequence position 3 of the week of days scale. 23. In clause 12.3, in the entry for Thursday, REPLACE the Definition and the Necessity: Definition: day of week in sequence position 4 of the week of days scale Necessity: Each Thursday is met by a Wednesday. with: Definition: calendar day period that is met by a Wednesday Necessity: The concept .Thursday. is the day of week that is in sequence position 4 of the week of days scale. 24. In clause 12.3, in the entry for Friday, REPLACE the Definition and the Necessity: Definition: day of week in sequence position 5 of the week of days scale Necessity: Each Friday is met by a Thursday. with: Definition: calendar day period that is met by a Thursday Necessity: The concept .Friday. is the day of week that is in sequence position 5 of the week of days scale. 25. In clause 12.3, in the entry for Saturday, REPLACE the Definition and the Necessity: Definition: day of week in sequence position 6 of the week of days scale Necessity: Each Saturday is met by a Friday. with: Definition: calendar day period that is met by a Friday Necessity: The concept .Saturday. is the day of week that is in sequence position 6 of the week of days scale. 26. In clause 12.3, in the entry for Sunday, REPLACE the Definition and the Necessity: Definition: day of week in sequence position 7 of the week of days scale Necessity: Each Sunday is met by a Saturday. with: Definition: calendar day period that is met by a Saturday Necessity: The concept .Sunday. is the day of week that is in sequence position 7 of the week of days scale. Disposition: Resolved Date: Thu, 4 Oct 2012 13:09:02 -0400 From: Ed Barkmeyer Reply-To: Organization: NIST User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) To: OMG DateTimeVoc FTF Subject: Re: DTV Issue 16944 draft resolution -- definitions of months and weekdays (named time points) X-NISTMEL-MailScanner-Information: Please contact postmaster@mel.nist.gov for more information X-NISTMEL-MailScanner-ID: q94H97LI010301 X-NISTMEL-MailScanner: Found to be clean X-NISTMEL-MailScanner-SpamCheck: X-NISTMEL-MailScanner-From: edbark@nist.gov X-NISTMEL-MailScanner-Watermark: 1349975348.30277@mUUIqBJUEkrzvp4BAGAvPw X-Spam-Status: No Actually, I realize now that using 'calendar day period' in the definitions of weekdays might be circular. It assumes that some other time scale defines a calendar day time point that makes the time interval a 'calendar day period', because we are defining a time point that does exactly that. That is, a time interval cannot be a Tuesday without also being the nth of the month. I don't think that is a good practice. So, I attach a revised resolution that eliminates the 'calendar day period' stuff. This also obviates the need for any UML change. -Ed Ed Barkmeyer wrote: All, The original of this draft, showing just the intended pattern, was distributed on 15 June. Hearing no objections, I have written up the full version. The proposed changes reorganize and correct the wording of the definitions and necessities for the named time points, like January and Tuesday. If someone wants a change to the pattern, speak now, before it goes to ballot. There is an issue in the writeup. It introduces the concept 'calendar day period' -- a time interval that some calendar day time point corresponds to -- just to shorten some of the definitions. It is not clear whether the concept is generally useful, and without it the definitions just grow a second characteristic: "and that has a duration that is one day". Is it worth adding this concept, or should we just remove those changes? Also, if anyone notes other errors in the writeup, please mention them. Thanks, -Ed -- Edward J. Barkmeyer Email: edbark@nist.gov National Institute of Standards & Technology Systems Integration Division, Engineering Laboratory 100 Bureau Drive, Stop 8263 Tel: +1 301-975-3528 Gaithersburg, MD 20899-8263 Cel: +1 240-672-5800 "The opinions expressed above do not reflect consensus of NIST, and have not been reviewed by any Government authority." DTV Issue 16944-weekday definitions-d3.docx Disposition: Resolved OMG Issue No: 16944 Title: Weekday definitions are inadequate Source: Ed Barkmeyer, NIST, edbark@nist.gov Summary: The definitions of the weekdays in 9.5.6 simply identify them as 'day of week' time points. ('day of week' is erroneously represented as a name instead of a noun concept) What is being defined in the text is apparently the individual time point, but the UML diagram shows that each day of week time point is in fact a general concept (that corresponds to time intervals). The text should make this clear. Further, the delimiting property for each of these concepts is specified in a Necessity that is intended to be taken as part of the definition: e.g., Each Tuesday is met by a Monday. That is, the intended definition of the general concept 'Tuesday' is: time interval that is an instance of a calendar day and that is met by an instance of Monday. The definition of the individual concept "Tuesday" is: the time point that has index 2 in the week of days scale, and that is the concept 'Tuesday'. Somehow the text has to make these two definitions clear. It takes significant effort for the reader to understand that the individual 'Tuesday the time point' can have instances, so that "each Tuesday" makes sense. It may be sufficient to phrase the Necessity as: Each instance of (time point) Tuesday is met by an instance of (time point) Monday. (SBVR Annex C provides a notation [Tuesday] to refer to the concept as a thing, and CLIF has no problem with the designation (symbol+concept) playing both predicate and argument roles.) Finally, the following Necessity should appear under 'calendar day' in 9.5.3: For each calendar, each instance of a 'calendar day' that is defined by the calendar is met by at most one instance of a calendar day that is defined by the calendar. Otherwise, the ontology could technically permit a day to be both a Tuesday and a Friday. It may be that this follows from the necessities for the relationships of the time scales to the Time Axis. If so, the Necessity is not needed, but a Note should mention the sequencing rules. Resolution: The last element above, the missing axiom, is added to clause 10.2. The FTF agrees that the Necessities in 12.3 (was 9.5.6) do not follow from the definitions, and they are not quite accurate as concept definitions: For example, a time interval is a Tuesday if and only if it is a Gregorian calendar day and is met by a Monday. The current definitions just state facts about the concepts. So the text is revised to define the time points as concepts and state their positions in the time scale as Necessities. This problem was found to apply to the definitions of Gregorian months in 11.3 (was 9.5.5) as well, and this resolution corrects those definitions similarly. In order to simplify the definition expressions, an abstract concept .time interval. is introduced. Revised Text: 1. In clause 11.3, change the styling for .January., .February., .March., .April., .May., .June., .July., .August., .September., .October., .November., and .December. from .name. (double underscore) to .term. (single underscore) in all occurrences. 2. In clause 11.3, in the entry for January, REPLACE the Definition and the first four Necessity paragraphs: Definition: Gregorian month of year in sequence position 1 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each January is met by the last Gregorian day of month of a December. Necessity: Each January starts a Gregorian year. Necessity: January has 31 Gregorian days of month. Necessity: The duration of each January is 31 days. with: Definition: time interval that has duration 31 days and that starts an instance of a Gregorian year Necessity: The concept .January. is the Gregorian month of year that is in sequence position 1 of the Gregorian year-of-months scale. Necessity: The time point .January. has 31 Gregorian days of month. Necessity: Each January is met by a December. 3. In clause 11.3, in the entry for February, REPLACE the Definition and the first five Necessity paragraphs: Definition: Gregorian month of year in sequence position 2 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each February is met by the last Gregorian day of month of a January. Necessity: If the Gregorian year is a leap year, then February has 29 Gregorian days of month. Necessity: If the Gregorian year is a common year, then February has 28 Gregorian days of month. Necessity: The duration of each February that is of a leap year is 29 days. Necessity: The duration of each February that is of a common year is 28 days. with: Definition: time interval that is met by a January and that has a duration that is 28 days if the time interval is part of an instance of a common year, or that is 29 days if the time interval is part of an instance of a leap year Necessity: The concept .February. is the Gregorian month of year that is in sequence position 2 of the Gregorian year-of-months scale. Necessity: The time point .February. has 29 Gregorian days of month. 4. In clause 11.3, in the entry for March, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 3 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each March is met by the last Gregorian day of month of a February. Necessity: March has 31 Gregorian days of month. Necessity: The duration of each March is 31 days. with: Definition: time interval that is met by a February and that has a duration that is 31 days Necessity: The concept .March. is the Gregorian month of year that is in sequence position 3 of the Gregorian year-of-months scale. Necessity: The time point .March. has 31 Gregorian days of month. 5. In clause 11.3, in the entry for April, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 4 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each April is met by the last Gregorian day of month of a March. Necessity: April has 30 Gregorian days of month. Necessity: The duration of each April is 30 days. with: Definition: time interval that is met by a March and that has a duration that is 30 days Necessity: The concept .April. is the Gregorian month of year that is in sequence position 4 of the Gregorian year-of-months scale. Necessity: The time point .April. has 30 Gregorian days of month. 6. In clause 11.3, in the entry for May, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 5 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each May is met by the last Gregorian day of month of an April. Necessity: May has 31 Gregorian days of month. Necessity: The duration of each May is 31 days. with: Definition: time interval that is met by an April and that has a duration that is 31 days Necessity: The concept .May. is the Gregorian month of year that is in sequence position 5 of the Gregorian year-of-months scale. Necessity: The time point .May. has 31 Gregorian days of month. 7. In clause 11.3, in the entry for June, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 6 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each June is met by the last Gregorian day of month of a May. Necessity: June has 30 Gregorian days of month. Necessity: The duration of each June is 30 days. with: Definition: time interval that is met by a May and that has a duration that is 30 days Necessity: The concept .June. is the Gregorian month of year that is in sequence position 6 of the Gregorian year-of-months scale. Necessity: The time point .June. has 30 Gregorian days of month. 8. In clause 11.3, in the entry for July, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 7 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each July is met by the last Gregorian day of month of a June. Necessity: July has 31 Gregorian days of month. Necessity: The duration of each July is 31 days. with: Definition: time interval that is met by a June and that has a duration that is 31 days Necessity: The concept .July. is the Gregorian month of year that is in sequence position 7 of the Gregorian year-of-months scale. Necessity: The time point .July. has 31 Gregorian days of month. 9. In clause 11.3, in the entry for August, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 8 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each August is met by the last Gregorian day of month of a July. Necessity: August has 31 Gregorian days of month. Necessity: The duration of each August is 31 days. with: Definition: time interval that is met by a July and that has a duration that is 31 days Necessity: The concept .August. is the Gregorian month of year that is in sequence position 8 of the Gregorian year-of-months scale. Necessity: The time point .August. has 31 Gregorian days of month. 10. In clause 11.3, in the entry for September, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 9 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each September is met by the last Gregorian day of month of an August. Necessity: September has 30 Gregorian days of month. Necessity: The duration of each September is 30 days. with: Definition: time interval that is met by an August and that has a duration that is 30 days Necessity: The concept .September. is the Gregorian month of year that is in sequence position 9 of the Gregorian year-of-months scale. Necessity: The time point .September. has 30 Gregorian days of month. 11. In clause 11.3, in the entry for October, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 10 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each October is met by the last Gregorian day of month of a September. Necessity: October has 31 Gregorian days of month. Necessity: The duration of each October is 31 days. with: Definition: time interval that is met by a September and that has a duration that is 31 days Necessity: The concept .October. is the Gregorian month of year that is in sequence position 10 of the Gregorian year-of-months scale. Necessity: The time point .October. has 31 Gregorian days of month. 12. In clause 11.3, in the entry for November, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 11 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each November is met by the last Gregorian day of month of an October. Necessity: November has 30 Gregorian days of month. Necessity: The duration of each November is 30 days. with: Definition: time interval that is met by an October and that has a duration that is 30 days Necessity: The concept .November. is the Gregorian month of year that is in sequence position 11 of the Gregorian year-of-months scale. Necessity: The time point .November. has 30 Gregorian days of month. 13. In clause 11.3, in the entry for December, REPLACE the Definition and the first three Necessity paragraphs: Definition: Gregorian month of year in sequence position 12 of the Gregorian year-of-months scale Necessity: The first Gregorian day of month of each December is met by the last Gregorian day of month of a November. Necessity: December has 31 Gregorian days of month. Necessity: The duration of each December is 31 days. with: Definition: time interval that is met by a November and that has a duration that is 31 days Necessity: The concept .December. is the Gregorian month of year that is in sequence position 12 of the Gregorian year-of-months scale. Necessity: The time point .December. has 31 Gregorian days of month. Necessity: Each December finishes an instance of a Gregorian year. 14. In clause 12.3, change the styling for .Monday., .Tuesday., .Wednesday., .Thursday., .Friday., .Saturday. and .Sunday. from .name. (double underscore) to .term. (single underscore) in all occurrences. 15. In clause 12.3, in the entry for Monday, REPLACE the Definition and the Necessity: Definition: day of week in sequence position 1 of the week of days scale Necessity: Each Monday is met by a Sunday. with: Definition: time interval that starts an instance of a calendar week and that has a duration that is 1 day Necessity: The concept .Monday. is the day of week that is in sequence position 1 of the week of days scale. 16. In clause 12.3, in the entry for Tuesday, REPLACE the Definition and the Necessity: Definition: day of week in sequence position 2 of the week of days scale Necessity: Each Tuesday is met by a Monday. with: Definition: time interval that is met by a Monday and that has a duration that is 1 day Necessity: The concept .Tuesday. is the day of week that is in sequence position 2 of the week of days scale. 17. In clause 12.3, in the entry for Wednesday, REPLACE the Definition and the Necessity: Definition: day of week in sequence position 3 of the week of days scale Necessity: Each Wednesday is met by a Tuesday. with: Definition: time interval that is met by a Tuesday and that has a duration that is 1 day Necessity: The concept .Wednesday. is the day of week that is in sequence position 3 of the week of days scale. 18. In clause 12.3, in the entry for Thursday, REPLACE the Definition and the Necessity: Definition: day of week in sequence position 4 of the week of days scale Necessity: Each Thursday is met by a Wednesday. with: Definition: time interval that is met by a Wednesday and that has a duration that is 1 day Necessity: The concept .Thursday. is the day of week that is in sequence position 4 of the week of days scale. 19. In clause 12.3, in the entry for Friday, REPLACE the Definition and the Necessity: Definition: day of week in sequence position 5 of the week of days scale Necessity: Each Friday is met by a Thursday. with: Definition: time interval that is met by a Thursday and that has a duration that is 1 day Necessity: The concept .Friday. is the day of week that is in sequence position 5 of the week of days scale. 20. In clause 12.3, in the entry for Saturday, REPLACE the Definition and the Necessity: Definition: day of week in sequence position 6 of the week of days scale Necessity: Each Saturday is met by a Friday. with: Definition: time interval that is met by a Friday and that has a duration that is 1 day Necessity: The concept .Saturday. is the day of week that is in sequence position 6 of the week of days scale. 21. In clause 12.3, in the entry for Sunday, REPLACE the Definition and the Necessity: Definition: day of week in sequence position 7 of the week of days scale Necessity: Each Sunday is met by a Saturday. with: Definition: time interval that is met by a Saturday and that has a duration that is 1 day Necessity: The concept .Sunday. is the day of week that is in sequence position 7 of the week of days scale. Disposition: Resolved