Comment 4 for bug 632267

(a) FontForge warning: The glyph named mu is mapped to U+00B5.
    But its name indicates it should be mapped to U+03BC.
  The glyph named Delta is mapped to U+2206.
    But its name indicates it should be mapped to U+0394."

the 'mu' is mapped to x00B5 since this was the historical WinANSI and MacUS character code point and PostScript name. The Greek x03BC is giving the name 'uni03BC' in accordance with Adobe's recommendations for glyph names.

(b) FontForge warning: The glyph named fi is mapped to U+F001.
    But its name indicates it should be mapped to U+FB01.
  The glyph named fl is mapped to U+F002.
    But its name indicates it should be mapped to U+FB02."

Glyph 'fl and fi' were originally assigned (by Apple;TrueType spec 1.0) to the Unicode 'private use area' xF001 and xF002 which became an industry standard characters and Unicode values.

The Unicode Consortium at the time did not consider the fi or fl to be valid Unicode characters because they are ligatures and made from 2 existing Unicode characters.

Later Unicode changed its mind and assigned two new values of xFB01, xFB02 for the 'fi' and 'fl' ligatures. For backward compatibility reasons the 'fi' and 'fl' should exist in all fonts and retain their values of xF001 and xF002 and two new glyphs are added and name 'f_i' and 'f_l' also to follow the Adobe recommendations for naming ligatures.