analog(optional)Contains a reference to a field or element in another descriptive encoding system
                                             to
                                             which this MEI element is comparable.
                                             Value is plain text.
                                             
                                    class(optional)Contains one or more URIs which denote classification terms that apply to the entity
                                             bearing this attribute.
                                             One or more values from data.URI, separated by spaces.
                                              
                                    copyof(optional)Points to an element of which the current element is a copy.
                                             Value conforms to data.URI.
                                              
                                    corresp(optional)Used to point to other elements that correspond to this one in a generic
                                             fashion.
                                             One or more values from data.URI, separated by spaces.
                                              
                                    follows(optional)points to one or more events in a user-defined collection that are known to be
                                             predecessors of the current element.
                                             One or more values from data.URI, separated by spaces.
                                              
                                    label(optional)Captures text to be used to generate a label for the element to which it’s attached,
                                             a
                                             "tool tip" or prefatory text, for example. Should not be used to record document
                                             content.
                                             Value is plain text.
                                             
                                    n(optional)Provides a number-like designation that indicates an element’s position in a sequence
                                             of similar elements. May not contain space characters.
                                             Value conforms to data.WORD.
                                              
                                    next(optional)Used to point to the next event(s) in a user-defined collection.
                                             One or more values from data.URI, separated by spaces.
                                              
                                    precedes(optional)Points to one or more events in a user-defined collection that are known to be
                                             successors of the current element.
                                             One or more values from data.URI, separated by spaces.
                                              
                                    prev(optional)Points to the previous event(s) in a user-defined collection.
                                             One or more values from data.URI, separated by spaces.
                                              
                                    resp(optional)Indicates the agent(s) responsible for some aspect of the text’s transcription,
                                             editing, or encoding. Its value must point to one or more identifiers declared in
                                             the
                                             document header.
                                             One or more values from data.URI, separated by spaces.
                                              
                                    sameas(optional)Points to an element that is the same as the current element but is not a literal
                                             copy
                                             of the current element.
                                             One or more values from data.URI, separated by spaces.
                                              
                                    synch(optional)Points to elements that are synchronous with the current element.
                                             One or more values from data.URI, separated by spaces.
                                              
                                    type(optional)Designation which characterizes the element in some sense, using any convenient
                                             classification scheme or typology that employs single-token labels.
                                             One or more values of datatype NMTOKEN, separated by spaces.
                                             
                                    xml:base(optional)Provides a base URI reference with which applications can resolve relative URI
                                             references into absolute URI references.
                                             Value conforms to data.URI.
                                              
                                    xml:id(optional)Regularizes the naming of an element and thus facilitates building links between it
                                             and other resources. Each id attribute within a document must have a unique value.
                                             Value is a valid xml:id.