The function converts the old LinkageData representation into new representation. The old representation is a LinkageDataList type should be converted to the new LinkageDataMap.
LinkageDataMap function stores the records of LinkageData as DownValues of symbol (for example f).
f[AllID] returns all record identifier as a list of strings.
f[recID,ALLID] returns all sub-record identifier as list of strings. If the record does not have sub-records the function returns {}.
f[LinkageData] = True if symbol f is used as LinkageDataMap.