Alternative to colon in a time format

Question

ISO 8601 recommends the following format for a date and time:

2014-12-29T16:11:20+00:00 

I'm rather fond of this format since it allows for lexical ordering. But there is a small problem: some file systems don't allow colons in file names (at least not normally). ISO 8601 does allow for omitting the colons, but I would rather have some symbol there than have the numbers run together:

2014-12-29T161120+0000 

Does ISO 8601 allow for a symbol other than colons? I couldn't find any indication that it does. If not, is there another well recognized symbol I could use? (Perhaps another standard proposes such a symbol?)

Answer 1

There is none.

ISO 8601 only allows for a colon (:) for separating time components in the extended format:

The basic format is [hh][mm][ss] and the extended format is [hh]:[mm]:[ss].

There is no provision for an alternate extended format.

Answer 2

For combined date and time representations you must use basic format for both date and time or extended format for both date and time representations to comply with ISO 8601.

Examples of ISO 8601 compliant date and time representations:

2020-12-03T15:05:57+00:00 (extended) 2020-12-03T15:05:57Z (extended) 20201203T150557Z (basic) 

For maximum compatibility with various operating systems file naming requirements and ISO 8601 compliance I think the last example or something similar should work.

Reference: https://en.wikipedia.org/wiki/ISO_8601#Combined_date_and_time_representations