ISO 8601 ABNF grammar

[Chris Newman <Chris.Newman@xxxxxxxxxxxx>]

I did my best attempt to write a complete ABNF grammar for ISO 8601.
Incidentally, I suggest we don't use the complete grammar in the
calendaring specification, as I think it's far too complex.

I'll also note that if the "T" is omitted from date-time, as 8601 permits,
then the grammar is ambiguous.

I do not have access to the 1991 Corregendum at present.

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ISO 8601:1988 ABNF

Dates:

date-century      = 2DIGIT  ; 00-99
date-decade       =  DIGIT  ; 0-9
date-subdecade    =  DIGIT  ; 0-9
date-year         = date-decade date-subdecade
date-fullyear     = date-century date-year
date-month        = 2DIGIT  ; 01-12
date-wday         =  DIGIT  ; 1-7
date-mday         = 2DIGIT  ; 01-28, 01-29, 01-30, 01-31 based on month/year
date-yday         = 3DIGIT  ; 001-365, 001-366 based on year
date-week         = 2DIGIT  ; 01-52

datepart-fullyear = [date-century] date-year ["-"]
datepart-ptyear   = "-" [date-subdecade ["-"]]
datepart-wkyear   = datepart-ptyear / datepart-fullyear

dateopt-century   = "-" / date-century
dateopt-fullyear  = "-" / datepart-fullyear
dateopt-year      = "-" / (date-year ["-"])
dateopt-month     = "-" / (date-month ["-"])
dateopt-week      = "-" / (date-week ["-"])

datespec-full     = datepart-fullyear date-month ["-"] date-mday
datespec-year     = date-century / dateopt-century date-year
datespec-month    = "-" dateopt-year date-month [["-"] date-mday]
datespec-mday     = "--" dateopt-month date-mday
datespec-week     = datepart-wkyear "W" (date-week / dateopt-week date-wday)
datespec-wday     = "---" date-wday
datespec-yday     = dateopt-fullyear date-yday

date              = datespec-full / datespec-year / datespec-month /
		datespec-mday / datespec-week / datespec-wday / datespec-yday

Times:

time-hour         = 2DIGIT ; 00-24
time-minute       = 2DIGIT ; 00-59
time-second       = 2DIGIT ; 00-60
time-fraction     = ("," / ".") 1*DIGIT
time-numzone      = ("+" / "-") time-hour [[":"] time-minute]
time-zone         = "Z" / time-numzone

timeopt-hour      = "-" / (time-hour [":"])
timeopt-minute    = "-" / (time-minute [":"])

timespec-hour     = time-hour [[":"] time-minute [[":"] time-second]]
timespec-minute   = timeopt-hour time-minute [[":"] time-second]
timespec-second   = "-" timeopt-minute time-second
timespec-base     = timespec-hour / timespec-minute / timespec-second

time              = timespec-base [time-fraction] [time-zone]

date-time         = date ["T"] time

Durations (periods):

dur-second        = 1*DIGIT "S"
dur-minute        = 1*DIGIT "M" [dur-second]
dur-hour          = 1*DIGIT "H" [dur-minute]
dur-time          = "T" (dur-hour / dur-minute / dur-second)
dur-day           = 1*DIGIT "D"
dur-week          = 1*DIGIT "W"
dur-month         = 1*DIGIT "M" [dur-day]
dur-year          = 1*DIGIT "Y" [dur-month]
dur-date          = (dur-day / dur-month / dur-year) [dur-time]

duration          = "P" (dur-date / dur-time / dur-week)

Periods:

period-explicit   = date-time "/" date-time
period-start      = date-time "/" duration
period-end        = duration "/" date-time

period            = period-explicit / period-start / period-end