Apache Reference: mod_autoindex, AddIconByEncoding

AddIconByEncoding

Image for File Icon (by MIME Encoding)
Syntax: AddIconByEncoding icon mime-enc [mime-enc ...]
Example: AddIconByEncoding (icons/compress.xbm x-compress
Since: Apache 1.0

This directive is similar to AddIcon, except that a MIME encoding is used for matching purposes instead of a file. The mime-enc argument is a wildcard expression matching the required content encoding.