This command associates file names or extensions (for services that don't automatically
include them) with mime types. Currently only "file:" protocol uses this command.
Use optional first two parameters to choose comparison type. Default type is
"String" "NoCase" (case sensitive string may use "?" and "*" as wildcards for one
and several characters correspondingly).
You may also use quotes in mime type definition, for example to specify charset.
e.g. Russian webmasters often use *.htm extension for windows-1251 documents and
*.html for Unix KOI8-r documents.