Where does "Rolemaster: The Basics" fit in? (The copy I have has a copyright date of 1995).
It is part of the
3rd edition of Rolemaster (sometimes called 'Rolemaster Standard System' [RMSS] or 'Rolemaster Fantasy-Roleplaying' [RMFRP]), which was published in the mid-1990s.
Fans of Rolemaster tend to be split between 'Rolemaster 2e' (now being published as 'Rolemaster Classic,' of which 'Rolemaster Express' is a simplified version) and 'Rolemaster Standard System'. The latter is a more complicated ('crunchy') system.
MERP is based on Rolemaster 2e (now Rolemaster Classic), as is Rolemaster Express.
Myself, I find Rolemaster 2e/Classic to be too 'rules heavy' for my current tastes (so RMSS/RMFRP is obviously beyond the pale). If I were to play Rolemaster again (something I hope to do, someday), I'd use
Rolemaster Express, with some supplementary material.