These commands are displayed only if a text layer is present.
In the Text to Selection drop-down list, the commands are identical to those of the Transparency sub-menu (in fact, the text is formed of areas of different transparency):
Text to Selection: Section 7.39, “Alpha to Selection”
Add to Selection: Section 7.40, “Add Alpha channel to Selection”
Subtract from Selection: Section 7.41, “Subtract from Selection”
Intersect with Selection: Section 7.42, “Intersect Alpha channel with Selection”