Apple II text mode uses the 7-bit ASCII (us-ascii) character set.
The high-bit is set to display in normal mode on the 40x24 text screen.
Each 5x7 pixel bitmap matrix is displayed in a 7x8 character cell on the text screen.
To display lowercase letters, applications can run in the graphics modes and use custom fonts, rather than running in text mode using the font in ROM.
The characters unique to MouseText are encoded in Unicode's Symbols for Legacy Computing block.