acknowledgment received : what is AN6?

I got my acknowledgment letter today.

In that it mentions type of application as AN6. I know this as Form AN. what does number 6 signify?


NCS or Postal: NCS Catford
Date of submission or posting: 30th April 2009
CRITERIA: 6 yr stay (5 yr WP, HSMP + 1 yr ILR)
Date of receipt of Application @ HO: 1st May 2009
Date of debit of debit/credit card: 11th May 2009
Date of receipt of acknowledgement: 13th May 2009 (Dated: 9th May)
Date of receipt of approval: Waiting
Invitation Letter: Waiting
Date of Ceremony: Waiting
Date of appln. for passport: Waiting
Interview for Passport : Waiting
Passport received: Waiting

could not get through to check with HO, Any idea guys?

6 yearsss?

Wild guess, though.

Perhaps it refers to the relevent section of the nationality act i.e. 6(1) or 6(2) ??