I set the max-age using

ExpiresActive On
ExpiresByType image/gif A36000
ExpiresByType image/png A36000
ExpiresByType application/x-javascript A36000
ExpiresByType application/javascript A36000
ExpiresByType text/css A36000

However, I furthermore wish to have Cache-control: public be looking for these mime-types to permit caching of those types by proxies.

I know of

<FilesMatch "\.(jpg|gif|png|js|css)$">
    Header append Cache-Control "public"

but I wish to get it with respect to the mime type that the application server behind Apache is properly setting, and never the file title or extension that might change.