The function query-registry-key-info
returns a plist of information about the open registry key handle key. The elements of the plist info are:
A string naming the class of the key, if any.
An integer giving the number of subkeys.
An integer giving the length of the longest subkey name.
An integer giving the length of the longest class name.
An integer giving the number of values.
An integer giving the length of the longest value name.
An integer giving the length of the longest value data.
An integer giving the length of the security descriptor.
LispWorks User Guide and Reference Manual - 20 Sep 2017