That seems like a reasonable explanation. This becomes even more plausible, given that the Twiggy Mac's front bezel has the same marking.
-Tom

On Monday, February 10, 2014 2:54:32 PM UTC-5, lincol...@gmail.com wrote:
I would guess that the "PTA" is the name of the manufacturer that made the plastic bezel for Apple.  I'm basing this on the fact that the T is somewhat taller than the P and A, looks like a logotype to me - maybe this company (http://www.ptaplastics.com/page.php?id=500), they've been around since the 1950s, are based in the U.S., and list Apple as one of their customers.

On Tuesday, January 7, 2014 1:21:24 PM UTC-5, Tom Frikker wrote:
Hello,
Both of the Lisa 2 Bezels that I own right now (the third Lisa's on its way) both have "PTA Prototype" molded inside the front bezel. Does anyone know what this means, if anything?

--
--
-----
You received this message because you are a member of the LisaList group.
The group FAQ is at http://lowendmac.com/lists/lisa.html
To post to this group, send email to lisalist@googlegroups.com
To leave this group, send email to lisalist+unsubscribe@googlegroups.com
For more options, visit this group at http://groups.google.com/group/lisalist
---
You received this message because you are subscribed to the Google Groups "LisaList" group.
To unsubscribe from this group and stop receiving emails from it, send an email to lisalist+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.