Fixed parameter validation error due to invalid regular expression.

The previous expression:
	/^[A-Za-z]|\[0-9\]$/
meant:
	The line starts with letters OR line ends with one of [,],0,-,9

The new expression:
	/^[A-Za-z0-9]$/
means:
	The line starts with and ends with a single character that is a letter or number.