In 64-bit LispWorks there are two methods of garbage collection: mark and sweep (also referred to simply as mark ) and copy . The two methods can be mixed within the same garbage collection operation and generation, but a segment is collected using only one of mark or copy in a given operation.
When a segment is collected using the copying method, the objects within it can either be copied to another segment in the same generation or can be copied to a segment in a higher generation. The latter case is called promotion. The automatic garbage collection copies with promotion until the objects reach the blocking generation, which is collected in a specific way as described in Generation Management.