The TEI provides the following for defining a new character:
charDesc of the encodingDesc section in the
teiHeader is a list of character definitions:char holds a definition of a charactercharName is a required childcharPropgraphicmapping to another character can be defined, a type is
used to indicate the type of the mapping according to some typology.More information can be found in Representation of non-standard characters and glyphs (which is currently Chapter 25 of the TEI Guidelines)
The character thus defined can then be invoked using the g element, the
required ref has to point to the definition in the header.