Hi, Bruce
A warm welcome to Apple Disacussions!
Check out these Mac OS X 10.4 Help Articles:
]
Why isn't a certificate being accepted?
]
Adding certificates to a keychain
Also,
here're the results from a google/Mac search for { keychain "X509 Anchors" }. From a quick glance, looks as if there are plenty that will help to answer your questions.
If you have further questions, I suggest you use the Apple KnowledgeBase "advanced"
search (or look to the purple bar at the top of this page for this link) I received 53 results from a search for all documents containing "keychain" and about the product: Mac OS X 10.4 (Tiger).
Good luck!
Dean