Architecture variability can be expressed within the Catalog Information, contained in a noncritical extension.  From the same .cat file as the OSAttr example:

30 68 1e 04 00 4f 00 53   0h...O.S
02 04 10 01 00 01 04 5a   .......Z
32 00 30 00 30 00 30 00   2.0.0.0.
2c 00 58 00 50 00 58 00   ,.X.P.X.
38 00 36 00 2c 00 58 00   8.6.,.X.
50 00 58 00 36 00 34 00   P.X.6.4.
2c 00 56 00 69 00 73 00   ,.V.i.s.
74 00 61 00 58 00 38 00   t.a.X.8.
36 00 2c 00 56 00 69 00   6.,.V.i.
73 00 74 00 61 00 58 00   s.t.a.X.
36 00 34 00 2c 00 37 00   6.4.,.7.
58 00 38 00 36 00 2c 00   X.8.6.,.
37 00 58 00 36 00 34 00   7.X.6.4.
00 00                     ..

A Vista Security Catalog may be accepted as valid on a 7 system within the same architecture, even if '2:6.1' is not explicit within the OSAttr variable, as long as it contains '2:6.0'.
This could help explain why many Vista drivers can be 'seen' as WHQL on Win7 systems of similar architecture.

I see that a previously mentioned Intel ME Management engine had no such noncritical extension embedded, and apparently was verified as WHQL.  Can anyone tell me how the noncritical extension can influence this behavior or point to some relevant info,  as i still don't fully understand all of the circumstances when & why a Vista .cat file can work with Win7.