Yes, this is the scribal pi. ’omega1’ is a misleading name that occurs in the Adobe Glyph List.

Whether you call it /uni03D6/ or /pi.salt/ depends on whether you want Acrobat to map it back to the regular pi character or to U+03D6. Of course, you could include a redundant glyph in your font and use both names, which would be very Adobe-like.

which would be very Adobe-like

that’s too funny, john. thanks for your input. a follw-up question, does it matter if this alternate form maps back to pi? is this simply a stylistic alternate?

Currently we’re using pi.alt as the friendly work name, and uni03D6 as the final name.

The reason why this glyph got named omega1 at some point, is most likely because it resembles omega (U+03C9).

...does it matter if this alternate form maps back to pi? is this simply a stylistic alternate?

Historically, yes, it is just a stylistic alternate, one of many. Some of the Greek stylistic alternates have been used in modern times as symbols in mathematics and the sciences, which is why some of them are separately encoded in Unicode. The scribal pi is one of these.

I think in the majority of cases, unless specifically making a font for use in scientific documents, you would probably this glyph to map back to the regular pi, and not to U+03D6.

Consider: a user creates a document in Greek and uses OpenType Layout features to access stylistic alternates including the scribal pi. Through some chain of circumstances, a PDF is created that contains only raw glyph IDs, no Unicode strings. Acrobat parses the glyph IDs to try to reconstruct the text for searching and copy/paste operations. If the scribal pi is mapped back to U+03D6, the text is no longer in Greek, and cannot be reliably searched.

Of course, if you are creating a scientific document and are using the character U+03D6 in your text to signify something with a semantic difference to pi, then you have the opposite problem if the scribal pi gets mapped back to the regular pi by Acrobat.

This is why Adobe’s glyph redundancy model isn’t really crazy after all.

The reason why this glyph got named omega1 at some point, is most likely because it resembles omega (U+03C9).
From left to right: omega, pi.alt and pi (from Garamond Premier Pro).

I suspect that in case of Garamond Premier Pro and many other fonts, the inverse is also true: U+03D6 is drawn as omega with a swoosh to the left instead of the scribal pi-like form with horizontal bar because of the wrong postscript name and other misleading associations with omega. This omega with a swoosh might have even became a modern tradition in itself, even though it has no greek scribal roots.

One does see the ’swoosh’ form for pi in some Greek handwriting, sometimes with a returning stroke, creating a loop across the top of the omega-like shape. This occurs in quickly written text, not a carefully written scribal book hand. I don’t think it is an ideal form for a typeface.