Genicom GEK 00031B Programmer's Manual page 91

Underline
GEK-00029B
Character Underlining: Enables or disables automatic underlining of
all characters.
Format
<SFCC> - <n>
Decimal: <SFCC> 45 <n>
Hex: <SFCC> 2D <nH>
BASIC: <CHR$(<SFCC>);"-<n>";
n = 0 disables automatic underlining (hex 00 or hex 30)
n = 1 enables automatic underlining (hex 01 or hex 31)
Details
When automatic underline is enabled, all characters, including
spaces, are underlined until the feature is disabled.
91
5000 Series Programmer's Manual