This clause describes the DSSSL transformation language.
Syntactically, the DSSSL transformation language is a data
content notation as defined by ISO 8879.
The content of an element in this notation is parsed as a
 transformation-language-body = unit-declaration*
A transformation process requires a single grove as input, which is
transformed as specified by the associations. An association may
cause other groves to be transformed. The grove being transformed is
referred to as the current grove.