This is the AFMS for the GNS530W with version 5.03 software update. They added specific support in the AFMS for PRNAV and compliance statements re AC-90-105 and AC-90-100A, etc.
Previously only the GTN units had this in the AFMS.
The 430W and the 530W come with an AML STC. This AFMS is an update and a complete rewrite of the original version. It only applies if the software in the GNS430W/530W is version 5.03. The software update is optional from version 3.3 to 5.03 and is not a mandatory change. It includes some new capabilities as the GNS530W/430W may now be used as an FAA approved position source for ADSB with the Garmin GDL88 or the GTX330ES/33ES - presumably this is relevant to the USA only. It also supports crossfill with the GTN.
I believe this is usable for N-reg only.
With thanks to NCYankee 
What's the process of applying a new AFMS to one's installation?
Normally a new AFMS means a Major Alteration, which thus always means a 337, and you have two options
If you have an airframe-specific STC (which in this case you have - an AML STC) the 337 is sent, together with the STC, to the FAA in Oklahoma for filing
If you do not have an STC (or one exists but it doesn't cover your airframe) then it's a Field Approval and you apply to an FSDO (or with more complicated stuff to an ACO) to approve it, and then you send the approved job off for filing
In both cases, an IA has to sign off the 337 before it is sent off.
The AFMS is supposed to be customised to your actual aircraft. I have done this job twice here and here (both as a Field Approvals) and in both cases the FAA inspectors were quite fussy. With an AML STC you just get a generic AFMS which you print off to size, cut out as required, punch holes in, and insert into your flight manual...
One merely has to print out the AFMS, fill in a few blanks. Make a log book entry, GNS530W AFMS revision B removed and replaced by GNS530W AFMS revision C. The software update is performed by an avionics shop and they should not charge more than an hour of labor, two hours if they are jerks. Any Garmin dealer can order the update chips for $100 USD for the pair ($50 each), one for Main Software version 5.03 and one for GPS software 5.0. The chips may be used on any number of updates by the avionics shop and the $50 is a deposit which they can get refunded if they return the chips to Garmin in a few years from now. The update is approved under a revision of the existing STC and a new 337 is not required.
GNS users can expect that to take months for EASA to approve. We are still waiting for GTN Software V3.0 despite a visit by Garmin US to EASA HQ to try to unblock things recently. The delay has been so long GTN V4.0 is coming out now (which includes Litres at last not just gallons/pounds of fuel).
Let's face it, EASA is a slow motion car crash like the rest of the EU!
It is very common to install these firmware updates as soon as they are FAA approved, even on EASA aircraft.
