%xinclude.ent; XInclude Module for BITS

Module that sets up the namespace and elements for using <xi:include> to manage books and book parts.
Declaration
<!ENTITY % xinclude.ent
                        PUBLIC
"-//NLM//DTD BITS XInclude Setup Module v2.1 20220202//EN"
"BITS-xinclude2-1.ent"                                                 >