Low Compression Motor

[Greg Mahney <mahney@central.murdoch.edu.au>]

My Sprite has a "low compression" motor   ie it is the wrong engine for the
car, but it was designed to be a "low compression" version of the A-series.
 This is evidenced by the engine number which is:

9D-U-L-105729  (the "L" is for LOW")

My question is What makes it "low compression".  is it the type of head?,
shorter stroke?  different pistons?  

Anyone know the answer to this one?

Many thanks

Greg