Every sequence respective its name receives a unique identifier.
<!ATTLIST SequenceDescription seqid ID #REQUIRED>
All information can be assigned to its corresponding sequence by way of a reference to the previously mentioned identifier.
<!ATTLIST SequenceInformation seqref IDREF #REQUIRED>
Length information is given for the complete sequence and for every kind of type.
<!ATTLIST Length type (sequence|%type;) #REQUIRED>
For every type, the total number of bases is stored which are contained in that particular type.
<!ATTLIST TotalNumber type %type; #REQUIRED>
As was shown in Section 9.2, a block groups together excerpts of sequences. These excerpts can be considered aligned or unaligned as denoted by their type.
<!ATTLIST Block type %type; #REQUIRED>
Every sequence (fragment) references one of the descriptions.
<!ATTLIST OneSequence seqref IDREF #REQUIRED>
All sequence data are annotated whether they may contain gaps as indicated by the gap character '-' or whether they are guaranteed to be free of gaps. Anchors and unaligned gaps are of type ``gapfree''.
<!ATTLIST SequenceData type (gapfree|gapped) #REQUIRED>