Apache Reference: mod_ssl, SSLCACertificateFile
File of PEM-Encoded CA Certificates for Client Authentication
Syntax: SSLCACertificateFile A
Example: SSLCACertificateFile etc/ssl/all.crt
Since: Apache 1.3
This directive sets the all-in-one file where you can assemble
the certificates of the certification authorities of those clients
with which you deal. These certificates are used for client authentication.
The file is simply the concatenation of the various PEM-encoded
certificate files, placed in order of preference. This directive can be used
as an alternative to or in conjunction with SSLCACertificatePath.