The type code-coverage-data is a structure containing information about code coverage.
code-coverage-data contains information about some set of files. With the exception of the internal code coverage data, code-coverage-data does not change after it is created. The internal code coverage data contains information about all files that have been loaded with code coverage (since the last call to clear-code-coverage). A file is "with code coverage" when it is a binary file compiled with code coverage on (see generate-code-coverage).
The counters in the internal code coverage data are the counters that the actual code is referencing, and therefore they are modified whenever any of this code is executing. For each file the counters are either actual counters or binary flags (see counters argument in generate-code-coverage), but inside the structure there may be files of either counter type.
All other code-coverage-data structures start their life as copies of the internal code coverage data, and then they can be further manipulated. They are displayed by code-coverage-data-generate-coloring-html or the LispWorks IDE.
The name is supplied to the data when it is created by functions like copy-current-code-coverage, and the create-time is the universal time when the data was created. These values are provided so that you can track your data: they are not used by the system. name can be any Lisp object, but normally should be a symbol or a string (because if you save the data name will be written too, so it is best if does not point to a large structure).
LispWorks User Guide and Reference Manual - 13 Feb 2015