External media (pdf, doc, html, txt) is tricky. External media is always detected as links to local files in the content of a TYPO3 page which is being indexed. But external media can the linked to from more than one page. So the index_section table may hold many entries for a single external phash-record, one for each position it's found. Also it's important to notice that external media is only indexed or updated if a "parent" TYPO3 page is re-indexed. Only then will the links to the external files be found. In a searching operation external media will be listed only once (grouping by phash), but say two TYPO3 pages are linking to the document, then only one of them will be shown as the path where the link can be found. However if both TYPO3 pages are not available, then the document will not be shown.