I have seen some typefaces with their names ending in PE behind.
I know PICA is a measure unit, but what about PE?
PE stands for Pan-European and refers to the character set or variety of glyphs you will find in the font.
For example, there is an interesting article about the development of Skolar Sans PE here: https://www.rosettatype.com/blog/2016/02/02/Skolar-Sans-Pan-European
From Fontshop: https://www.fontshop.com/content/language-support
Pan-European 1 (W06)
Character set: Latin Extended + Cyrillic + Greek
Supported languages: As above plus Avar, Balkar, Belarusian, Bulgarian, Chechen, Erzya, Ingush, Lezgian, Macedonian, Moldavian, Ossetian, Russian, Serbian, Ukrainian, Greek