Guides can be dragged from the rulers (see Display Options)


drag from rulers  create a guide
drag from rulers command create a global guide (font level guide)
drag alt rotate guide 
mouse over cursor changed with guide values
drag over point in glyph stick to that point
drag out of the view delete the guide 
Contextual menu
Name name for the guide
Position center point of the guide x, y coordinate
Angle angle of the guide
Is Global Make the guide global (on font level) or local (only used in one glyph).
Display Measurements Display where the guides touches the glyph.
Magnetic Determine how fast a dragged selection should snap to the guide. 
Lock Guides Lock all guides
Lock Images Lock all images
Slice Glyph slice the glyph by the guide
Delete Guide Delete the guide