You can use ^ and %, but must enter them in the _Alphanumeric variable twice as ^^ or %%. However, if you want to use the result (_RndAlphaNum) later in the batch file (other than Echoing to the screen), they might require special handling. You can even use a space, as long as it's not the last character in the string.
23 inches (59cm) is the minimum distance required for a chair behind a desk. This would fit a modest sized chair. For more comfort and to accommodate a bigger office chair increase the chair clearance to 30 inches (76cm). Office Chair tips. Swivel chairs make it easier to get in and out from behind your desk, especially if the space is a bit tight.
The height of the chair should be about 12 inches less than the height of the table. Therefore, chairs at traditional 30-inch tables should measure 18 inches. Bar stool seats are either 24 inches or 30 inches above the ground, depending on the height of the bar-style table.