The optional .ddd is to specify milliseconds and is acceptable on any of the forms above, even though only shown on one.
Omitted time-zone shall be interpreted as UTC. This deviates from the iso-8601 specification which specifies no time zone information to be interpreted as local time.
Values will be comma separated. This will allow for little loss of bandwidth for missing values.
Data values other than date will be in any format acceptable to the ANSI C string-to-double function strtod(3).
Recommend to implemetors to use appropriate significant figures.
inf and nan are acceptable.
Fields not supplied or available will be left empty (e.g. '...,4.523,,48.234,...').
Optionally can be terminated by \r\n (carriage return, newline).