A change package contains a set of entries, each of which (usually) has the same form as a patch (see Patch and Patch From on page 227). But change package entries can be
modified (added to) after they are first created. Such modified entries don't fit the "recent changes" description of a patch. Rather, a change package entry can act like an accumulator, recording
all the changes made to the element to fulfill a particular development task. The change package facility was designed to track exactly what element-by-element changes go into the bug fix or feature that the issue record describes, and to answer questions such as these: