tex.math.delims — Should equations output for processing by TeX be surrounded by math mode delimiters?
For compatibility with DSSSL based DBTeXMath from Allin Cottrell you should set this parameter to 0.
You can also use the <?dbtex delims?> processing
instruction to control whether delimiters are output.
For how-to documentation on embedding TeX equations and generating output from them, see DocBook XSL: TCG, DBTeXMath.