Decimal fractions may be added to any of the three time elements. Of these, the comma is the preferred sign. Its appearance depended on the particular packaging, canning, or bottling plant more than any particular brand. It therefore represents years from 0000 to 9999, year 0000 being equal to 1 and all others. There is no limit on the number of decimal places for the decimal fraction. The , as of 2006, appeared in its basic form on major brand commercial packaging in the United States. The week number can be described by counting the Thursdays: week 12 contains the 12th Thursday of the year.
If the interval specifies the start forms 1 and 2 above , then this is the start of the repeating interval. If a time zone designator is required, it follows the combined date and time. In representations for interchange, dates and times are arranged so the largest temporal term the year is placed to the left and each successively smaller term is placed to the right of the previous term. Even within a single geographic time zone, some local times will be ambiguous if the region observes. It is usually preferable to indicate a time zone zone designator using the standard's notation. While it may be safe to assume local time when communicating in the same time zone, it is ambiguous when used in communicating across different time zones. It explicitly excludes durations and dates before the.
The capital letters P, Y, M, W, D, T, H, M, and S are designators for each of the date and time elements and are not replaced. The amount of intervening time is expressed by a duration as described in the previous section. The standard also allows for calendar dates to be written with reduced accuracy. Date and time elements including their designator may be omitted if their value is zero, and lower order elements may also be omitted for reduced precision. The format is particularly useful for quality assurance, so that production errors can be readily traced to work weeks, and products can be correctly targeted for recall. Java Platform Standard Edition 8. However, years prior to are not automatically allowed by the standard.
This format is used with simple hardware systems that have a need for a date system, but where including full calendar calculation software may be a significant nuisance. . The standard states that every date must be consecutive, so usage of the would be contrary to the standard because at the switchover date, the dates would not be consecutive. This format will never represent the 5th day of an unspecified month in 2004, nor will it represent a time-span extending from 2004 into 2005. A solidus is a and not allowed in a filename in common operating systems. Sausalito, California: University Science Books.
Use of a double hyphen instead of a solidus allows inclusion in computer. However, individual date and time values cannot exceed their e. If the interchange character set is limited and does not have a minus sign character, then the hyphen—minus should be used. The section dictating sign usage section 3. The purpose of this standard is to provide an unambiguous and well-defined method of representing dates and times, so as to avoid misinterpretation of numeric representations of dates and times, particularly when data are transferred between for writing numeric dates and times. The time may be represented using a specified reduced accuracy format. The Gregorian calendar today serves as an international standard for civil use.
As a consequence, if 1 January is on a Monday, Tuesday, Wednesday or Thursday, it is in week 01. Earlier dates, in the , may be used by mutual agreement of the partners exchanging information. If greater precision is desirable to represent the time interval, then more time elements can be added to the representation. It soon may be possible to write international standards documents with decimal points in them. Either basic or extended formats may be used, but both date and time must use the same format. This allows dates to be naturally by, for example, file systems. This enables reference to dates and times in calendar years outside the range supported by complete representations, i.
If the interval specifies the end but not the start form 3 above , then this is the end of the repeating interval. By mutual agreement of the partners in information interchange, it is permitted to expand the component identifying the calendar year, which is otherwise limited to four digits. If 1 January is on a Friday, Saturday or Sunday, it is in week 52 or 53 of the previous year there is no week 00. Time: From Earth Rotation to Atomic Physics. The two time points start and end are expressed by either a combined date and time representation or just a date representation. The of the representation thus corresponds to chronological order, except for date representations involving negative years or time offset. Decimals Score a Point on International Standards.
If the character set has a minus sign, then that character should be used. However, a fraction may only be added to the lowest order time element in the representation. In addition, dates and times to be represented cannot include words with no specified numerical meaning in the standard e. Although the standard describes durations as part of time intervals, which are discussed in the next section, the duration format is widely used independent of time intervals, as with the Java 8 Duration class. The date expression may be calendar, week, or ordinal, and must use a complete representation.