Versioning, patchs, working with CVS

IF (you decide to make a change on P1_X) AND (P1_X is the latest closed version of P1) {
        Compare project P1_X with the project P1_Head;
        IF (P1_X identical to P1_Head) {
                Load P1_Head code;
        }
        ELSE {
                IF (P1_Head code is worth loading/using) {
                 Load P1_Head code;
                 Compare P1_Head with P1_X, and merge changes if needed to code in workspace;
                 //You have now a open edition of P1 in workspace which is a merge of P1X and P1H
                } ELSE {
                 jump to case B; 
                }
        }
        Continue development;
}

You want to make a patch on a project…

• The version of the project has already been deployed or sold to customer, and
• Your actual code may be a lot more advance, but not finished, not tested, possibly breaking interfaces of other components and
• You prefer to continue development on the old version to reduce risks of instabilities.

//old status of a project which have a problem/your prefer  Load P1_X in workspace;  (Team - replace with - choose version P1_X) 
On P1_X, create a branch (Team - create branch - name it for ex: P1_X_b01);
Develop, test, develop;
Commit the branch (Team - commit : this put code in its own HEAD)
When the branch is stable, create a version P1_X_1 for example (Team - Tag as verion)

Decide if now if the change done on P1_X_1 are worth to bring in P1_Head, if so You will have to follow Case A