Why would there be Multiple FDLs and Implementations?
(from Dec 1 Seminar)

Basic motives for creating a particular certification system instead of relying on an existing one can be expected to include:

• Accessibility - one may simply be incapable or undesiring of access to an other wise suitable certification system. Maybe access is unreliable. Maybe one wants to develop formal texts in isolation on a laptop for a while. Or maybe one must work in a more secure computational environment than is already provided.
• Integrity - perhaps one has doubts about the integrity of an available certification system either be cause of particular doubts about it or because of non-specific doubts about the competency of the implementors or the security of their infrastructure.
• Independence - the existence of independent compatible systems is a benefit to the entire community of clients because it provides some antidote to loss of accessibility or integrity of individual systems; the threat of dependency fosters a legitimate reluctance to invest in a commons of certification systems.
• Limited Mission - a provider may decide to focus its effort on certain limited aspects of certificati on systems in order to guarantee integrity, or to control its limited resources. One organization might focus on library and archival functions, providing little direct support for text development, and thus relying on the existence of other development oriented systems for uploads. Another might emphasize development of formal texts by a small community, and therefore, although it has the functionality to implement archives, it refuses to commit to the storage of and public access to texts not pertinent to its own text development.
• Experimental Design of Certification Systems.

Remark: These are taken from section 3.7 of TR Abstract Identifers & Textual Reference