Did I find the right sentence ?

All symbol names defined in a PBC program are similarly defined in
assembly, but with the name preceded with an underscore ( _ ). This
allows access to user variables, constants, and even labeled locations, in
assembly. Similarly, system variable (such as W0) names are also
preceded by underscores (such as _W0).

so my wonderfull TOTO var byte
will be known by my ASM code as _TOTO ?

life is wonderfull

RTFM you said ! you are right !
Francois