Why does the ISO-8601 specification appear to be universally ignored when it comes to decimals? [closed]

Answer 1

RFC3339, as defined by the IETF specifies only the . as a delimiter.

Here's section 5.6:

5.6. Internet Date/Time Format

   The following profile of ISO 8601 [ISO8601] dates SHOULD be used in
   new protocols on the Internet.  This is specified using the syntax
   description notation defined in [ABNF].

   date-fullyear   = 4DIGIT
   date-month      = 2DIGIT  ; 01-12
   date-mday       = 2DIGIT  ; 01-28, 01-29, 01-30, 01-31 based on
                             ; month/year
   time-hour       = 2DIGIT  ; 00-23
   time-minute     = 2DIGIT  ; 00-59
   time-second     = 2DIGIT  ; 00-58, 00-59, 00-60 based on leap second
                             ; rules
   time-secfrac    = "." 1*DIGIT
   time-numoffset  = ("+" / "-") time-hour ":" time-minute
   time-offset     = "Z" / time-numoffset

   partial-time    = time-hour ":" time-minute ":" time-second
                     [time-secfrac]
   full-date       = date-fullyear "-" date-month "-" date-mday
   full-time       = partial-time time-offset

   date-time       = full-date "T" full-time

Answer 2

A pure ISO-8601-compliant parser MUST support both comma and dot. The comma is not strictly required, only recommended. So regarding this standard the given examples of JavaScript, PHP, Ruby etc. clearly indicate an error of those parser implementations.

RFC3339 indeed only supports a subset (excluding the comma AND also excluding decimal hours or decimal minutes!) - so not fully ISO-compliant.

XML-schema is similar. It excludes the comma, unfortunately (see the W3C-document).

So you ask why? That is my suspicion: Programming world is strongly dominated by US. In US culture the dot is used as decimal separator in numbers. So most people developing such frameworks, standards and libraries are sitting in US and mistakenly think that dots are quasi an international standard.

So the question remains, why ISO uses/recommends the comma? I don't know it exactly, but we all know the office of ISO group is located in Paris, not in US. And in Europe (excluding UK) the comma is generally preferred as decimal separator, also a cultural aspect.

Finally, not all parsers are wrong. At least Joda-Time supports comma, too, although preferring the dot in printing. What is the situation in NodaTime? I hope at least similar to Joda-Time. Please keep supporting parsing of comma. From an european perspective it is nice to see that not all stuff looks like american ;-).