Class binding and loading attributes

Each class is bound into a separately relocatable loadable segment, using one of two binding attributes.

Classes containing parts use merge binding (described at Parts (z/OS and CMS)). Parts are the smallest independently relocatable components of a merge class.
Classes not containing parts use concatenation binding, in which elements, after suitable alignment, are placed one after another. Zero-length elements are retained but take no space in the program object. Elements are the smallest independently relocatable components of a concatenation class

Each class must have uniform binding and loading attributes. More than one class can have identical attributes, and the binder can put such classes into one segment. The most usual class attributes are RMODE, alignment, and Loadability; see CATTR instruction (z/OS and CMS) for further information.

Class loading attributes determine the load-time placement of segments in virtual storage. Loadable segments are loaded as separately relocated non-contiguous entities at different origin addresses.