chickadee » srfi-14 » char-set:lower-case

char-set:lower-caseconstant

The lower-case ASCII characters are

 abcdefghijklmnopqrstuvwxyz

For Unicode, a character is lower-case if it has a Lowercase property.

Some Unicode lowercase characters:

03B1GREEK SMALL LETTER ALPHA
0431CYRILLIC SMALL LETTER BE
2170SMALL ROMAN NUMERAL ONE