  This note concerns Legendrian cobordisms in one-jet spaces of functions, in
the sense of Arnol'd \cite{Arnold}
  -- consisting of big Legendrian submanifolds between two smaller ones. We are
interested in such cobordisms which fit with generating functions, and wonder
which structures and obstructions come with this notion. As a central result,
we show that the classes of Legendrian concordances with respect to the
generating function equipment can be given a group structure. To this
construction we add one of a homotopy with respect to generating functions.
