RFC 5545, "Internet Calendaring and Scheduling Core Object Specification (iCalendar)", September 2009Source of RFC: calsify (app)
Errata ID: 3457
Reported By: Johannes Raggam
Date Reported: 2013-01-16
Rejected by: Barry Leiba
Date Rejected: 2013-01-16
Section 3.2 says:
Property parameter values that contain the COLON, SEMICOLON, or COMMA character separators MUST be specified as quoted-string text values.
It should say:
Property parameter values that contain the COLON, SEMICOLON, COMMA or SPACE character separators MUST be specified as quoted-string text values.
Section "3.2.2. Common Name" gives an example with an double-quoted parameter value with a SPACE in it:
That example also shows a double-quoted parameter value with a "J" in it, but that doesn't mean that values that contain "J" MUST be quoted. Examples are just examples, and any value MAY be quoted.
The ABNF is the definitive source. The ABNF at the bottom of page 10 and top of page 11 (Section 3.1) says that non-quoted values may contain any number of characters from the SAFE-CHAR set, and that set includes WSP (SP and HTAB; see RFC 5234). Quoting is not required on account of space characters.