Model for the processing alternatives element (<alternatives>)
<!ENTITY % alternatives-model "(%alternatives-display.class; | map-group | %math.class;)+" >
(array | chem-struct | graphic | inline-graphic | inline-supplementary-material | media | textual-form | preformat | private-char | supplementary-material | table | map-group | tex-math | mml:math)+
bookcustom-models3.ent