Texas Nightowl and others may be interested to know that FamilySearch recommends redirecting to ARK type URLs. This stands for Archival Resource Key, and the URLs are intended to be persistent. I think this means basically permanent unless a serious mistake is made by the engineers. See the articles at these links: https://familysearch.org/developers/docs/guides/persistent-identifiers, https://familysearch...ent-identifiers , https://familysearch...des/redirecting. Here is an example link for accessing a page using an Archival Resource Key,: https://familysearch...03/1:1:KF1F-RV9.
These ARKs should be a safe way to reference material on FamilySearch without too much fear of the URL changing.