ft_ssl_issuer

Certificate chain member for the server. Supply the entire chain, including the CA root certificate. The server reads the certificates in the chain in the order they are presented in this parameter. 

ft_ssl_issuer = chain_member

The certificates must be in PEM, DER, PKCS#7, or PKCS#12 format. A DER format file can only contain a single certificate; it cannot contain a certificate chain. See File Names for Certificates and Keys for more information on file types for digital certificates.