Synthetic processes are provided wherein oligomeric compounds are prepared having phosphodiester, phosphorothioate, phosphorodithioate, or other covalent linkages. Methods for making the resulting biocompatible crosslinked polymers biodegradable or not are provided, as are methods for controlling the rate of degradation. Further, the elastic material filling the notches 23e enlarges the joined portion between the plate member 23b and the gasket 24b. Tags, for example, may be associated to the files, and a subjective level of importance may be assigned to each tag.