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.
Height. Comfortable or standard chair height is about 17 inches. If your seat or bench is intended for comfortable sitting with feet on the floor, it will need to be standard chair height. A bench in a child's bedroom or playroom can be lower to accommodate smaller legs.Benches intended to serve as daybeds or cozy curling-up spots can be as high as you like. 10- to 20-inch-high bench back with or without cushions provides a finished look, further comfort and fills any wall space between the seat and window.