[pdftex] Version of pdfTeX User Manual

[Suresh Govindachar]

Hello,

A) The Version of the pdfTeX manual at pdftex.org is January 1, 2007 
Rev. 1.671;  and its Section 1.1 starts with "This manual revision 
(1.671) tries to keep track with the recent pdfTEX development up to 
version 1.40.0."  Same is true of the manual in my local MikTeX 
installation.

B) However, I also have a pdfTeX manual with Version November 23, 2010 
Rev. 655;  and its Section 1.1 starts with "This manual revision (655) 
tries to keep track with the recent pdfTeX development up to version 
1.40.11."

Judging by the date of the Version and the Version mentioned in the 
first sentence of Section 1.1, B is newer than A.

Question:  Why is the Version of B "655" and that of A "1.671"?  How are 
these numbers to be compared?

Thanks,

--Suresh