In this paper we present the concepts of drawn
symbolic picture and symbolic picture. Such notions have been conceived as an
extension of the concept of drawn pictures which was introduced by Maurer,
Rozenberg and Welzl [31]. We provide a string description of such pictures. It
consists of alternating words, i.e. strings whose letters are in alternation
from an alphabet of symbols and an alphabet of moves. We analyze the complexity
of the description language of a (drawn) symbolic picture and show how these
yield context-sensitive, context-free and regular languages. Then, we
characterize the grammars for alternating words and define the generative model
for (drawn) symbolic pictures. Moreover, we investigate the different types of
ambiguity that occur when dealing with symbolic grammars. Finally, we propose a
classification for symbolic picture grammars and languages.