name of grand piano part

[Richard West]

I want to know the "official," "most used" name for the part of a grand
piano that positions the key frame left to right.  It's that block at
the left hand side of the key bed.  It usually is held in place with
screws, is covered with felt, and can be shimmed to position the
keyboard and stack farther to the right when appropriate.  I couldn't
find the part listed in "Piano Parts and Their Functions."  Possible
names might be:  keyboard rest block, keyboard positioning block. 
What's the right name for that part?

Richard West