pubmed_190101.dtd: linebreakstyle attribute

Attribute: linebreakstyle

In <mml:mo>

linebreakstyle (before|after|duplicate|infixlinebreakstyle) #IMPLIED

In <mml:mstyle>

linebreakstyle (before|after|duplicate|infixlinebreakstyle) #IMPLIED

In <mml:math>

linebreakstyle (before|after|duplicate|infixlinebreakstyle) #IMPLIED