Taxonomy Guidelines

naming conventions
- namespace.hyphenated-attribute
- no nested namespaces
- no camel case
- if the value has a unit of measure, include that in the attribute name (e.g. size-bytes)
ext
- non-core/one-off attributes must be prefixed with the ext namespace: ext.namespace.attribute
  - this is the only exception to nesting
  - ext is not hyphenated
- may include format-specific attributes, these should always represent the original values as closely as possible
internal
- functionally scoped (e.g. ui, registry)
- may be treated as a prefix like ext if necessary
- all other guidelines still apply
- these namespaces should not be documented as part of the taxonomy and are for developer use only
criteria for adding an attribute to the core taxonomy
- two or more congruent usages
  - at least two formats that both define and use the attribute to mean the same thing
- well-defined
- where applicable
  - standards-based (e.g. Dublin Core)
  - must define a unit of measure
- name should be format-independent
- fully implemented
  - transformer support
  - side effects (e.g. security)