In the old CAA (not JAR) way of things, in addition to passing all the ATPL's, you had to pass a performance exam as well which was appropriate to the type you wanted on your BCPL / CPL / ATPL.
There were Perf A, B,C,D,E and a few others. Basically E was light singles, C was light twins and A was jet airliners. Can't remember what the others were.
Most people sat perf E with their initial sitting as it was the easiest, and most people would do their initial CPL skills test in something akin to a C152 or PA28, and had to be passed in order to get the c152 or pa28 on their licence.
So, in order to get something like a B757 type rating, you had to of first passed the Perf A exam (arguably the hardest). Airlines often have this as a pre-requisite as it takes some people months to study for it.