Does the standard specify the official C++ grammar?
I searched, but did not find it anywhere.
Also, I wish to read a bit about C++ grammar in detail, like which category of grammars it falls in, etc. Any links pointing me in the right direction would be helpful.
By category, I mean
taken from here.
Yes, it does.
The grammar is described in detail throughout the standard and is summarized in Appendix A: Grammar Summary (it's Appendix A in both the C++03 standard and the C++0x final committee draft).
You can purchase the C++03 standard or you can download the C++0x FCD (it's document n3092 on that page).
To answer the "what category is it in?" question, the C++ grammar is not context-free (also see the questions linked in answers to that question; they have additional examples of issues related to the C++ grammar and parsing C++).