Purpose
Match a minimum of 0 and a maximum of 1 node. Indicates element is optional.
Remarks
Short for min=0 max=1. opt, option and o are alternate forms for optional.
Example
_vgroup <- _modal [optional] _have [optional] _be [optional] _verb @@
optional
Original VisualText 2 documentation (2001–2013). For the current NLP++ tools, see visualtext.org.