Drawing is a manifestation of symbolic activity of
 man, that is, its ability to represent things by means of signs which
 constitute the substitutes of those things. For its nature, it’s intended
 to convey meanings among individuals who recognize it, it
 is therefore a means of communication. In this context, the project
 drawing has a place which is a means of communication by which
 information is transmitted through the reduction of the concept in
 concrete and legible signs.
 These signs semantically allow the reading and the perception
 of the orderly content that constitutes the signifier; such signs
 represent the elementary cell of the graph as binary action among
 two abstract classes of concepts: the meaning and the signifier. The
 first one (the meaning) is the mental image that is produced it,
 depends on the experience and is induced by the second (the signifier)
 which is the physical vehicle, concretely materialized with an
 ИСТОРИЯ НАУКИ И ТЕХНИКИ. БИОГРАФИИ
 In the past, the representation of design profited from
 some symbol-forms such «architectural orders» or building
 types, which were common and certain patterns, but
 with the changes of the nineteenth century, it has been
 assuming ever greater autonomy and symbolic-expressive
 capacities.
 The representation, endowed with a very articulated
 syntax, results fit to rather reproduce complex representations,
 such as the graphs of assemblage of metallic works
 or preparation for theirs single components, but also the
 diagrams for the temporal planning of the operations of
 yard. In the interpretation of the drawing, therefore,
 interesting to define the relationship between the content
 of the information and the characteristics of the communication
 medium.
 The versatile design allows you to articulate it in multiple
 uses, each expressed with a specific pattern; in the
 nineteenth century has gone by defining the division of
 the models into three classes, for the purposes of representation,
 which has largely remained unchanged up to
 us: the iconic models that communicate the concept
 trying to maintain the qualitative and quantitative aspects,
 the logic models that reproduce the phenomenon through
 the use of symbols and relations between them and the
 verbal patterns that represent the phenomenon by describing
 lexical character and properties. The latter have a
 dual nature, of instructions or information. Information
 go to complete the information of the representation with
 denominations, attributions of materials, dimensions,
 explanation of the characteristics of the surfaces of the
 conservation status. Instructions, serve to explain the
 context in which you put the subject of the representation
 with formal definitions and descriptions. It is easy to
 imagine that the oral model doesn´t exhaust him in a
 simple terminological description, but consists mainly of
 numerical specifications to a graphic support which they
 refer. In the drawing of project it doesn’t use a single
 model, but it is assisted to their mutual integration, with
 the prominence of one in comparison to the others according
 to the object represented of the period and of the
 professional sector which refers.
 In the given plans it’s evident the heterogeneity of the
 employed style; the different kind of the object does not
 affect the model: the bulkhead of a rail yard has markimage.
 The system of signs can be organized in a code when it
 allows the recipient an unambiguous interpretation of the written
 message. It becomes, therefore, necessary to determine the encoding
 used in the act of writing the graphics, in order to ensure an
 exact decoding, avoiding any possible ambiguity in the subsequent
 phase of reading.
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