Invoice number sequence

The same query i too had, as per this act, it has been said that one should use serial nos. on invoice but it also provides for "MULTIPLE" serial no. tax invoice book and there has been no clarification given on this regard. Hence according to me if a entity have two different branches he can use "A1,A2,A3......" for one branch and "B1,B2,B3...." For another.

Asper rule "a consecutive serial number, in one or multiple series, containing alphabets or numerals or special characters hyphen or dash and slash symbolised as “-” and “/” respectively, and any combination thereof, unique for a financial year;"

#vineeth sir.... then does it mean one can have more then one tax invoice book at same place or its branches ?

I have read rules of Invoice rule 1 (b) and multiple invoice sequence number allowed.
thanks