Revise Initials Release For Free

The most common revision systems are based on a numeric (1, 2, 3 ?) or alphabetic sequence (A, B, C ? AA, AB, AC ?). In some cases, numbers are used for revisions up to the 'For Construction' issue of documents, with letters used for revisions from that point on.

Version control is a component of software configuration management. Changes are usually identified by a number or letter code, termed the "revision number", "revision level", or simply "revision". For example, an initial set of files is "revision 1".

Rev A would be the first revision for formal release into production. Places I've worked that used "-" tended to go away from it after a while; I don't remember the arguments or reasons.

There are many kinds of revision numbering schemes. One that we commonly see is to use alpha characters (A - Z) for the drawing revisions prior to when the drawing is released as-constructed, then move to a numeric numbering system for operations and maintenance changes.

First release is revision "-". First revision to a released document is "A", and subsequent revisions increment by one letter. Skip letters "I", "O", "Q", "S", "X", "Z" After rev "Y" the next rev is "AA", and then (following the same rules still) the second letter increments for each revision (e.g. "AB", "AC", etc.)

Also stated in these standards, all letters in the alphabet can be used for revisions, except I, O, Q, S, X, and Z, as these can be mistaken for numbers. The letters are to be used in an uppercase format.

35M-1997 states that I, O, Q, S, X and Z should not be used as revision letters. In fact, other ASME engineering drawing standards also forbid the use of these letters for other purposes as well. The reason is that I, O, Q, S, and Z all can be misinterpreted as numbers 1, 0, 5 and 2.

An original document is un-revised and should be "0". When changes are made, it's revised and then follows rev (or vers) 1, 2, 3 etc.