  A program is usually represented as a word chain. It is exactly a word chain
that appears as the lexical analyzer output and is parsed. The work shows that
a program can be syntactically represented as an oriented word tree, that is a
syntactic program tree, program words being located both in tree nodes and on
tree arrows. The basic property of a tree is that arrows starting from each
node are marked by different words (including an empty word). Semantics can
then be directly specified on such tree using either requirements or additional
links, and adding instructions to some tree nodes enables program execution
specification.
