CWD -- change working directory
 PWD -- print  working directory

 SYNTAX:

	>CWD
	>CWD [DDNN:] [[G,M]]
	>CWD [.:] [ [.] [,.] ]
	>PWD

 All arguments to CWD are optional (device-unit, group-code, and member-
 code) and if not specified result in no change for the missing argument.
 the brackets around the uic are optional.

 CWD with no arguments resets default UIC and SY0: assignment to
 the login assignments.

 PWD prints the current working directory and space information
 on SY0:

 Type HELP CWD MORE for more information on CWD and PWD.
2 MORE
 CWD with one or more '.' specifiers is used to reset SY0: and
 UIC assignments to logon settings. A '.' specifier in any position
 tells CWD not to alter that particular setting; e.g. 

	>CWD .:,.

 will reset the group code to the logon setting, leaving SY0:
 and member assignments unaltered. No alpha-numerics are allowed
 if a '.' specifier is present anywhere in the command.

 CWD performs an ASN DDNN:=SY: and/or a SET /UIC=[G,M] on behalf
 of the issuing terminal. Note, however, that CWD will not change
 the login UIC for privileged terminals. This allows privileged
 terminals to issue CWD with no arguments to regain login settings.
 Experience seems to indicate that the system is not adversely 
 affected by this feature.

 In addition, if DDNN: is provided to CWD, free space information
 is printed for SY:.

 Volume space information for CWD and PWD involves checking that
 SY0: is mounted (and not marked for dismount) and public, along
 with the percentage of space currently allocated on the device
 and the total count of free blocks (this information comes directly
 from the device UCB and VCB, involving no i/o)

 For all forms of the command, and after checking volume information,
 search for the assigned working directory is made to see if the
 UFD actually exists. If it does not exist, a warning message is
 printed.