Dayo -
Service Release One was the first update released. People were having
trouble configuring it, so MS issued update 10.1.2 which incorporated
SR-1.
All subsequent updates show
Microsoft(R) <application> for Mac(R) Service Release 1
in the About box. It's rather a poor implementation of update
information in the About dialog.
From what I've seen over the years, MS typically releases a product,
then, as bug fixes/change in OS fixes/etc. accumulate, they issue a
Service Release (Service Pack for Windows Apps), about 6 to 12 months
after initial release which rolls up any previous updates. Usually, only
updates are made after that only as bugs are fixed, or, as in the case
of update 1.4, a significant new feature is introduced that can't wait
until the next version. Rarely, they'll issue a SR-2 to roll those up.