The Client Certificates tab contains three types of certificates:
Premium Certificates are almost always the best choice. A premium certificate is useful for personal
Client Authentication
Document Signing
Email Encryption
Email Signing
Don't use the Digital Signature Plus certificate; it is just a limited variant of Premium.
Email Security Plus offers the possibility to have your private key stored by DigiCert (escrow).
Both Premium Client Certificates and Document Signing Certificates can be use to sign documents. Certainly in an Adobe Acrobat environment there is a preference for Document Signing certificates.
Refer to the Documents page to find out more on how to issue client and grid certs using the 'by-hand process' model.