ERROR:

	When an error occurs during an RLaB session, it can be classed
	as one of two types. Either a parse error, or a run-time
	error. We will discuss both below.

	All error messages attempt to provide both file and line
	number information to help locate the error; unless the error
	occurs at the command line.

	Parse errors:

	A parse error is an error that occurs while RLaB is converting
	an expression to it's compiled form. Each statement that is
	typed at the command line prompt, or read from a file, is
	compiled, and then executed. If the error occurs during this
	conversion, the error message is predicated with the string
	"parse error".

	Run-time errors:

	A run-time error is any error that is not a parse error.
	Run-time errors occur during execution of the compiled
	statements. Run time error messages are predicated with the
	name of the executing program; usually "rlab".
