Identifiers in the dlf namespace are used to identify 
information assets used in Digital Library Federation 
research and development projects.

An  'info' URI with  namespace 'dlf' takes the form:

info:dlf/<dlf-project>/<project-specific-id>
 
dlf-project = ALPHA *( ALPHA | DIGIT )

i.e. alphanumeric with leading alphabetic character.

Values of dlf-project are assigned by the Digital Library Federation and
registered at http://diglib.org/namespace/Projects.txt.  At the time of this
registration the only valid dlf-project value is "Aquifer".

project-specific-id = project-specific-component *("/" project-specific-component) 

project-specific-component = *pchar 

pchar is as defined in RFC 3986, that is:

pchar  = unreserved | pct-encoded | sub-delims | ":" | "@"
unreserved    = ALPHA | DIGIT | "-" | "." | "_" | "~"
pct-encoded = "%" HEXDIG HEXDIG
sub-delims  = "!" | "$" | "&" | "'" | "(" | ")"  | "*" | "+" | "," | ";" | "="

ALPHA, DIGIT, AND HEXDIG are as defined in RFC 2234: upper 
or  lower case alphabetic (A-Z | a-z), decimal digit (0-9), 
and hexadecimal digit (DIGIT | "A" | "B" | "C" | "D" | "E" | "F")  respectively.

Percent Encoded Characters  

No characters in general need to be percent encoded. 

All identifiers in the dlf namespace are case-sensitive.

Identifiers in the dlf namespace are used to identify information assets
used in Digital Library Federation research and development projects.
Identifiers will vary according to project.  Their uses currently include:

* Target namespaces for XML Schema, for example: info:dlf/Aquifer/AssetActions/AssetDefinition/

* Identifiers for use in ontologies, for example RDF property labels, such as:
 info:dlf/Aquifer/AssetActions/getWebView

No service mechanisms are at present defined.