  We present a Sign Language modelling approach allowing to build grammars and
create linguistic input for Sign synthesis through avatars. We comment on the
type of grammar it allows to build, and observe a resemblance between the
resulting expressions and traditional semantic representations. Comparing the
ways in which the paradigms are designed, we name and contrast two essentially
different strategies for building higher-level linguistic input:
"source-and-forward" vs. "target-and-back". We conclude by favouring the
latter, acknowledging the power of being able to automatically generate output
from semantically relevant input straight into articulations of the target
language.
