An instance of a datatype that is defined as can have the following legal literals {true, false, 1, 0}.

The canonical representation for boolean is the set of literals {true, false}.

decimal has a lexical representation consisting of a finite-length sequence of decimal digits (#x30-#x39) separated by a period as a decimal indicator. An optional leading sign is allowed. If the sign is omitted, "+" is assumed.  Leading and trailing zeroes are optional. If the fractional part is zero, the period and following zero(es) can be omitted. For example: -1.23, 12678967.543233, +100000.00, 210.

The canonical representation for decimal is defined by prohibiting certain options from the .  Specifically, the preceding optional "+" sign is prohibited.  The decimal point is required. Leading and trailing zeroes are prohibited subject to the following: there must be at least one digit to the right and to the left of the decimal point which may be a zero.

float values have a lexical representation consisting of a mantissa followed, optionally, by the character "E" or "e", followed by an exponent.  The exponent be an . The mantissa must be a number. The representations for exponent and mantissa must follow the lexical rules for and .  If the "E" or "e" and the following exponent are omitted, an exponent value of 0 is assumed.

The special values positive and negative infinity and not-a-number have lexical representations INF, -INF and NaN, respectively. Lexical representations for zero may take a positive or negative sign.

For example, -1E4, 1267.43233E12, 12.78e-2, 12 , -0, 0 and INF are all legal literals for float.

The canonical representation for float is defined by prohibiting certain options from the .  Specifically, the exponent must be indicated by "E".  Leading zeroes and the preceding optional "+" sign are prohibited in the exponent. If the exponent is zero, it must be indicated by "E0". For the mantissa, the preceding optional "+" sign is prohibited and the decimal point is required. Leading and trailing zeroes are prohibited subject to the following: number representations must be normalized such that there is a single digit which is non-zero to the left of the decimal point and at least a single digit to the right of the decimal point unless the value being represented is zero. The canonical representation for zero is 0.0E0.

double values have a lexical representation consisting of a mantissa followed, optionally, by the character "E" or "e", followed by an exponent.  The exponent be an integer.  The mantissa must be a decimal number. The representations for exponent and mantissa must follow the lexical rules for and .  If the "E" or "e" and the following exponent are omitted, an exponent value of 0 is assumed.

The special values positive and negative infinity and not-a-number have lexical representations INF, -INF and NaN, respectively. Lexical representations for zero may take a positive or negative sign.

For example, -1E4, 1267.43233E12, 12.78e-2, 12 , -0, 0 and INF are all legal literals for double.

The canonical representation for double is defined by prohibiting certain options from the .  Specifically, the exponent must be indicated by "E".  Leading zeroes and the preceding optional "+" sign are prohibited in the exponent. If the exponent is zero, it must be indicated by "E0". For the mantissa, the preceding optional "+" sign is prohibited and the decimal point is required. Leading and trailing zeroes are prohibited subject to the following: number representations must be normalized such that there is a single digit which is non-zero to the left of the decimal point and at least a single digit to the right of the decimal point unless the value being represented is zero. The canonical representation for zero is 0.0E0.

Equality and order for are defined as follows:

Two numerical values are ordered (or equal) as their values are ordered (or equal).  (This means the two zeros with a given but different are equal; negative zeros are not ordered less than positive zeros.)

's lexical space is the set of all no-decimal-point, decimal, and scientific numerals, plus the character strings INF, +INF, -INF, and NaN.  (Lexical representations of numbers are traditionally called numerals.)  The notation constraining facet can remove any one or two of the three subsets of numerals, with corresponding reductions in the value space.  Using this facet rather than will change the canonical mapping to insure that the resulting datatype will still have canonical representations of all its values. Lexical Space precisionDecimalRep  |  |  |

Canonical mappings are not used during schema processing.  They are provided in this specification for the benefit of other users of these datatype definitions who may find them useful, and for other specifications which might find it useful to reference them normatively.

precisionDecimal has the following &cfacet;s:

fractionDigits

Durations can be modeled in at least two ways: as six-property tuples (similar to the seven-property model used for other date/time datatypes) or as two-property tuples (somewhat similar to the alternative one-property timeOnTimeline model especially useful for order).  For durations, it is useful to use the latter: values are two-property tuples.  (Note, however, that the six-property model was implicitly used in Schema 1.0.  The only effective difference to the user caused by this change is in the canonical representations.)  See for more information on the seven-property model. Properties of Values month second Must not be negative if is positive, and not be positive if is negative. is partially ordered.  Equality and order are defined in terms of that of , and are determined by adding each value pair in turn to the following four values:

1696-09-01T00:00:00Z

The lexical representations of are more or less based on the pattern: PnYnMnDTnHnMnS

More precisely, the of is the set of character strings that satisfy as defined by the following productions: Lexical Representation Fragments duYearFrag  Y duMonthFrag  M duDayFrag  D duHourFrag  H duMinuteFrag  M duSecondFrag ( | ) S duYearMonthFrag ( ?) | duTimeFrag T (( ? ?) | ( ?) | ) duDayTimeFrag ( ?) | Lexical Representation durationLexicalRep -? P (( ?) | )

Thus, a consists of one or more of a , , , , , and/or , in order, with letters P and T (and perhaps a -) where appropriate.

The production is equivalent to this regular expression -?P(((([0-9]+Y([0-9]+M)?)|
      (       ([0-9]+M) ) )(([0-9]+D(T(([0-9]+H([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)|
                                       (       ([0-9]+M) ([0-9]+(\.[0-9]+)?S)?)|
                                       (                 ([0-9]+(\.[0-9]+)?S) ) ))?)|
                            (       (T(([0-9]+H([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)|
                                       (       ([0-9]+M) ([0-9]+(\.[0-9]+)?S)?)|
                                       (                 ([0-9]+(\.[0-9]+)?S) ) )) ) )?)|
    (                      (([0-9]+D(T(([0-9]+H([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)|
                                       (       ([0-9]+M) ([0-9]+(\.[0-9]+)?S)?)|
                                       (                 ([0-9]+(\.[0-9]+)?S) ) ))?)|
                            (       (T(([0-9]+H([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)|
                                       (       ([0-9]+M) ([0-9]+(\.[0-9]+)?S)?)|
                                       (                 ([0-9]+(\.[0-9]+)?S) ) )) ) ) ) ) once you delete the whitespace.  Redundant parehtheses are shown as ghosts; some find them helpful in reading the expression.)

The for is called herein, is defined as follows:.

The canonical mapping for is called herein, is defined as follows:.

The of dateTime consists of finite-length sequences of characters of the form: '-'? yyyy '-' mm '-' dd 'T' hh ':' mm ':' ss ('.' s+)? (zzzzzz)?, where

For example, 2002-10-10T12:00:00-05:00 (noon on 10 October 2002, Central Daylight Savings Time as well as Eastern Standard Time in the U.S.) is 2002-10-10T17:00:00Z, five hours later than 2002-10-10T12:00:00Z.

For further guidance on arithmetic with dateTimes and durations, see .

Except for trailing fractional zero digits in the seconds representation, '24:00:00' time representations, and timezone (for timezoned values), the mapping from literals to values is one-to-one. Where there is more than one possible representation, the canonical representation is as follows:

The 2-digit numeral representing the hour must not be '24';

Timezones are durations with (integer-valued) hour and minute properties (with the hour magnitude limited to at most 14, and the minute magnitude limited to at most 59, except that if the hour magnitude is 14, the minute value must be 0); they may be both positive or both negative.

The lexical representation of a timezone is a string of the form: (('+' | '-') hh ':' mm) | 'Z', where

The mapping so defined is one-to-one, except that '+00:00', '-00:00', and 'Z' all represent the same zero-length duration timezone, ; 'Z' is its canonical representation.

When a timezone is added to a dateTime, the result is the date and time "in that timezone".  For example, 2002-10-10T12:00:00+05:00 is 2002-10-10T07:00:00Z and 2002-10-10T00:00:00+05:00 is 2002-10-09T19:00:00Z.

dateTime value objects on either timeline are totally ordered by their timeOnTimeline values; between the two timelines, dateTime value objects are ordered by their timeOnTimeline values when their timeOnTimeline values differ by more than fourteen hours, with those whose difference is a duration of 14 hours or less being incomparable.

In general, the on dateTime is a partial order since there is no determinate relationship between certain instants. For example, there is no determinate ordering between (a) 2000-01-20T12:00:00 and (b) 2000-01-20T12:00:00Z. Based on timezones currently in use, (c) could vary from 2000-01-20T12:00:00+12:00 to 2000-01-20T12:00:00-13:00. It is, however, possible for this range to expand or contract in the future, based on local laws. Because of this, the following definition uses a somewhat broader range of indeterminate values: +14:00..-14:00.

The following definition uses the notation S[year] to represent the year field of S, S[month] to represent the month field, and so on. The notation (Q & "-14:00") means adding the timezone -14:00 to Q, where Q did not already have a timezone. This is a logical explanation of the process. Actual implementations are free to optimize as long as they produce the same results.

The ordering between two dateTimes P and Q is defined by the following algorithm:

A.Normalize P and Q. That is, if there is a timezone present, but it is not Z, convert it to Z using the addition operation defined in

B. If P and Q either both have a time zone or both do not have a time zone, compare P and Q field by field from the year field down to the second field, and return a result as soon as it can be determined. That is:

C.Otherwise, if P contains a time zone and Q does not, compare as follows:

D. Otherwise, if P does not contain a time zone and Q does, compare as follows:

Examples:

Certain derived types from dateTime can be guaranteed have a total order. To do so, they must require that a specific set of fields are always specified, and that remaining fields (if any) are always unspecified. For example, the date datatype without time zone is defined to contain exactly year, month, and day. Thus dates without time zone have a total order among themselves.

The lexical representation for time is the left truncated lexical representation for : hh:mm:ss.sss with optional following time zone indicator.  For example, to indicate 1:20 pm for Eastern Standard Time which is 5 hours behind Coordinated Universal Time (), one would write: 13:20:00-05:00. See also .

The canonical representation for time is defined by prohibiting certain options from the .  Specifically, either the time zone must be omitted or, if present