Liblouis User's and Programmer's Manual
2.6 Emphasis Opcodes ¶
In many braille systems emphasis such as bold, italics or underline is indicated using special dot patterns that mark the beginning and if needed also the end. Some braille systems have several indicators for different situations, i.e. an indicator for an emphasized word and another one for an emphasized phrase. To accommodate for all these usage scenarios liblouis provides a number of opcodes.
At the same time some braille systems use different indicators for
different kinds of emphasis while others know only one kind of
emphasis. For that reason liblouis doesn’t hard code any emphasis
types but the table author defines which kind of emphasis exists for a
specific language using the emphclass opcode (see emphclass).