Set height/width as a scale% value instead of pxl?

I am trying to set up my platformer character to crouch ("When Down arrow is down, Set height to X" on the Player object). But it seems to want a pixel value when what be more flexible is a % value, the way scale works.

I did a search and found references to OriginalHeight parameters in Construct Classic but I didn't have any success using them in Construct 2, though it's possible I didn't get the syntax right.

Is there a way set height and wight by percentage and if so, how do I do it? And if it is an unlisted parameter (like OriginalHeight) is there a comprehensive list of these commands somewhere?

Thanks.

player.ImageHeight and player.ImageWidth (assuming the player size = the image size)

The expressions are all in the manual:

Sprite expressions:

http://www.scirra.com/manual/115/sprite/page-1

Common expressions:

http://www.scirra.com/manual/133/common-expressions

That did the trick! And thanks for the links. I forgot that the Player object was also a sprite so I wasn't thinking of the Image related commands.