Hi Arijit,
That is an old (and incorrect) version of the Admin Guide. Did you download it recently? The link that you provided has been out of use for some time now.
The IGMP section in the current Admin Guide (available from www.cisco.com/go/srp500 [click on Maintain and Operate]) is on page 83 and does not refer to IGMP v3.
No document should refer to IGMPv3, as this has never been implemented for the SRP500 to date.
Regards,
Andy