The |fichier filter (since SPIP 1.4 ) can only be applied to a #LOGO tag. It returns the full access path to the file corresponding to the logo associated with the document.
Examples: [(#LOGO_DOCUMENT|fichier)] might return "prive/vignettes/pdf.png" (for the standard thumbnail in SPIP), or perhaps "local/cache-vignettes/L112xH54/my_file.png" (fora customised thumbnail), or even "png/image_1.png" (not a thumbnail at all).
Warning:
Although it is applied to a #LOGO tag, this filter can not be used with a double pipe (||fichier will not work) ;
Do not confuse this filter with the tag of the same name: #FICHIER.
Update:
This filter has been obsoleted in version SPIP 2.1, and the following syntax is preferred instead: #LOGO_DOCUMENT**.