Status: Passed, jun-87
Issue:        FORMAT-ATSIGN-COLON
References:   FORMAT description (p386)
Category:     CLARIFICATION
Edit history: Version 1 by Pitman 02/27/87
              Version 2 by cleanup committee 15-Mar-87
              Version 3 by Masinter 15-Mar-87
              Version 4 by Masinter  5-Jun-87

Problem Description:

CLtL describes the format op syntax as:

"a format directive consists of a tilde (~), optional prefix parameters separated by commas, optional colon (:) and atsign (@) modifiers, and a single character indicating what kind of directive this is."

CLtL uses :@ fairly consistently throughout without saying whether @: is legal. Is @: allowed?

Proposal (FORMAT-ATSIGN-COLON:OK):

There is no required ordering between the @ and : modifier.

Rationale:

This is currently underspecified, and this way of specifying it will cause the least disruption to user code.

Current practice:

Most implementations accept these in either order. Some implementations have been known to expect only :@.

Adoption Cost:

The change to accept either syntax is probably quite trivial.

Benefits:

Having @: and :@ mean different things would be awkward. 

Conversion Cost:

Existing user code would be unaffected.

Aesthetics:

Leaving these unordered is slightly simpler conceptually.

Discussion:

The cleanup committee supports this clarification.
