[1] They allow the attributes to be evaluated in one depth-first left-to-right traversal of the abstract syntax tree.
As a result, attribute evaluation in L-attributed grammars can be incorporated conveniently in top-down parsing.
A syntax-directed definition is L-attributed if each inherited attribute of
depends only on Every S-attributed syntax-directed definition is also L-attributed.
Implementing L-attributed definitions in Bottom-Up parsers requires rewriting L-attributed definitions into translation schemes.