The first time the Registrator runs (during the VX install) it prompts for the local WDIR folder location, and the value entered is stored into the WDIR_<product_root> environment variable. For example, PADS VX product root is "PADSVX.1.1" and therefore the variable name is WDIR_PADSVX_1_1 (replace periods/full-stops with underscores). The value of this variable becomes the "WDIR" once the applications launch (see TechNote MG586180 on SupportNet for more details).
When the Registrator next runs (launched from the Start Menu or via the Release Switcher) the WDIR prompt is populated based on the WDIR_<product name> environment variable. If you change the value, the variable is updated. Do NOT attempt to update the WDIR environment variable in the system area, as it will be over-written by the WDIR_<product_root> environment variable (e.g. WDIR_PADSVX_1 for PADS VX.1) as soon as the application launches.
While you can edit the WDIR_<product_root> environment variable in the system area , the recommended way to change the WDIR is to run the Release Switcher or Registrator.
Refer to the screen-shot below to see the relationship between the WDIR_<product root> variable and the WDIR prompt in the Registrator.