Syntax
where
The CLEARCH: command is used to remove the link between an
external input file and a channel number. Once the channel has been
freed, it may be reallocated to another external file. The first form of
the syntax is used to free input channels, and the second to free output
channels. Optionally, the argument may be placed within parentheses.
is an integer representing an input
channel number, and 
is an integer representing
an output channel number.
