  The article is an attempt to contribute to explorations of a common origin
for language and planned-collaborative action. It gives `semantics of change'
the central stage in the synthesis, from its history and recordkeeping to its
development, its syntax, delivery and reception, including substratal aspects.
  It is suggested that to arrive at a common core, linguistic semantics must be
understood as studying through syntax mobile agent's representing, tracking and
coping with change and no change. Semantics of actions can be conceived the
same way, but through plans instead of syntax. The key point is the following:
Sequencing itself, of words and action sequences, brings in more structural
interpretation to the sequence than which is immediately evident from the
sequents themselves. Mobile sequencers can be understood as subjects
structuring reporting, understanding and keeping track of change and no change.
The idea invites rethinking of the notion of category, both in language and in
planning.
  Understanding understanding change by mobile agents is suggested to be about
human extended practice, not extended-human practice. That's why linguistics is
as important as computer science in the synthesis. It must rely on
representational history of acts, thoughts and expressions, personal and
public, crosscutting overtness and covertness of these phenomena. It has
implication for anthropology in the extended practice, which is covered
briefly.
