I need a guideline or procedure which describe the version number policy for source code as per changes happened(major, minor, Micro), assigning particular version to release, labeling e.t.c
Your guideline in this regards will be highly appreciated....
You might want to look at the Wikipedia article relating this, here it is: http://en.wikipedia.org/wiki/Version_number
Follow the format a.b.c.d, a being Major, b Minor, c Build and d Revision (even though MS swaps those last two around).
Major and Minor should be set by yourself. Use Build and Revision or just Revision to relate back to the changeset/revision in your source control system.
Reason to use a combination of Build and Revision for this is because you may run into issues where the revision is too high a number to be used on certain platforms (thinking of AssemblyVersion in .NET here, 4 Int16 parts). So you could use SCS revision div 1000 for c and revision mod 1000 for d.
That way, from any version number (really just from Build and Revision parts), you will always be able to get to a unique state of your source code.
I've always been a fan of the way the Apache folks handle versioning. The Subversion people also adopted a variation of it (can't find the link since they moved web sites), which makes for a consistent, easy to understand methodology.