| @copyof(optional)Points to an element of which the current element is a copy.
                           Value conforms to data.URI .
                           att.common.anl | 
                  
                     | @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.
                           att.common.anl | 
                  
                     |  | 
                  
                     | @dur(optional)Records the duration of a feature using the relative durational values provided by
                              the data.DURATION datatype.
                           Value conforms to data.DURATION .
                           att.duration.musical | 
                  
                     | @facs(optional)Permits the current element to reference a facsimile surface or image zone which
                              corresponds to it.
                           One or more values from data.URI , separated by spaces.
                           att.facsimile | 
                  
                     | @form(optional)Describes the style of the tremolo.
                           Allowed values are:
                           "meas " (Measured tremolo.) ,  "unmeas " (Unmeasured tremolo.)att.fTrem.log | 
                  
                     | @label(optional)Provides a name or label for an element. The value may be any string.
                           Value of datatype string .
                           att.commonPart | 
                  
                     | @layer(optional)Identifies the layer to which a feature applies.
                           One or more values of datatype positiveInteger , separated by spaces.
                           att.layerident | 
                  
                     |  | 
                  
                     | @n(optional)Provides a number-like designation for an element.
                           Value conforms to token .
                           att.common | 
                  
                     | @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.
                           att.common.anl | 
                  
                     | @prev(optional)Points to the previous event(s) in a user-defined collection.
                           One or more values from data.URI , separated by spaces.
                           att.common.anl | 
                  
                     | @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.
                           att.common.anl | 
                  
                     |  | 
                  
                     | @staff(optional)Signifies the staff on which a notated event occurs or to which a control event
                              applies. Mandatory when applicable.
                           One or more values of datatype positiveInteger , separated by spaces.
                           att.staffident | 
                  
                     | @synch(optional)Points to elements that are synchronous with the current element.
                           One or more values from data.URI , separated by spaces.
                           att.common.anl | 
                  
                     | @tstamp(optional)Encodes the onset time in terms of musical time, i.e.,
                              beats[.fractional_beat_part].
                           Value conforms to data.BEAT .
                           att.timestamp.musical | 
                  
                     | @tstamp.ges(optional)Captures performed onset time in several forms; that is, ppq (MIDI clicks and
                              MusicXML 'divisions'), Humdrum **recip values, beats, seconds, or mensural duration
                              values.
                           Value conforms to data.DURATION.gestural .
                           att.timestamp.performed | 
                  
                     |  | 
                  
                     | @when(optional)Indicates the point of occurrence of this feature along a time line. Its value must
                              be the ID of a when element elsewhere in the document.
                           Value conforms to data.URI .
                           att.alignment | 
                  
                     | @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 .
                           att.commonPart | 
                  
                     | @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 of datatype ID .
                           att.id |