6.1.9.39.3 Class Flag
The class
psect flag specifies a corresponding linker
class name for this psect. A class is a range of addresses in which psects can be
placed.
Class names are used to allow local psects to be located at link time,
since they cannot always be referred to by their own name in a -P
linker
option (as would be the case if there are more than one local psect with the same
name).
Class names are also useful where psects need only be positioned anywhere within a range of addresses rather than at a specific address. The association of a class with a psect that you have defined typically means that you do not need to supply a custom linker option to place it in memory.
See 7.1.1 A: Define Linker Class Option for information on how linker classes are defined.