Apple defines the decimal 189 entry in the codepage MacOS Roman as follows: U+03A9, so it references the Greek Omega sign rather than the Ohm sign in the codepage. Adobe in their Glyph List for New Fonts (AGLFN) recommends that the glyphname "Omega" maps to U+2126 (Ohm sign), which means that the Greek Omega sign should have the glyph name "uni03A9". Most older Type 1 fonts used the glyph name "Omega" for the Ohm sign, and Adobe Type Manager on Mac OS 9 did indeed map the the glyph named "Omega" to MacOS Roman decimal position 189. This resulted in the fact that currently, the MacOS Roman encoding and the MacOS Roman codepage shipping with FontLab products are not compatible with each other.
We at Fontlab Ltd. would like font developers to participate in a small poll to answer the question: Should Fontlab Ltd. modify the MacOS Roman encoding file (mac_roman.enc) so that the mapping "Omega 189" is replaced with "uni03A9 189", which would meet all current recommendations by both Apple and Adobe?
The poll and more detailed explanation of the problem is posted on the FontLab forum: "Omega" vs. "uni03A9" glyph naming controversy
Please visit and give your vote!