We can, of course, distinguish two different meanings of communication. Communication may be understood in the sense that is given by defenders of semiology of communication, or how the information theory understands it. The fifties saw the birth of The mathematical theory of communication, by Shannon and Weaver (1949), and Fundamentals of language, by Jakobson and Halle (1956). Since then the term code attained its present success that is known of it: the Saussurian language-speech opposition is reformulated in terms of message-code; one speaks of phonological code, linguistic code, relationship code, aesthetic code, genetic code, analogical code (continuous) and digital code (discreet), ethnolinguistic, gestural, proxemic codes, etc.
The notion of code is as vast as the notion of sign: the Portuguese language code, numerical codes used in telephones and computer language, symbolical codes (of flowers or colours), regulations that allow us to deduce an illness from its symptoms, good manner rules, rules that allow us to deduce the social status or nationality of someone by the clothes s/he wears. There are uses of this notion that are not semiotic: the expression “civil code”. In the case of the expression “postal code”, for example, the word “code” refers to a relationship between signs – sequences of numbers/ - and something that these signs refer to: “a post office”. The expression “road code” shows both cases: on the one hand, it is a group of social rules, but on the other hand, some of these rules establish connections between road signs that are characterized by certain /colours/, /forms/ motifs/ and “indications”, “orders”, etc… in this case, it is a code in the semiotic sense of the term. The typology of cultures is based on the systems that provide it with its own consistency (Lotman 1969) and it must describe the main types of cultural codes in which “languages” of various cultures take form. Naturally, these social codes are institutions or value systems (like “honour”, “glory”). The typology of cultures oscillates, therefore, around the double meaning of code as institution and correlation. In both cases the code is a model of the world. Lotman distinguishes, moreover, cultures that we call hipo-codified, based on texts that propose models of behaviour and hyper-codified cultures based on textbooks or grammar books (Lotman and Uspenskij 1975).
The term code was used first in the information theory in which it designates an inventory of arbitrarily chosen, symbols accompanied by a group of rules of composition of codified “words”, and frequently parallel to a dictionary of natural language (cf. Morse). This is, in its simplest form, a derived artificial language. The hybridism of this term comes from the information theory which designates “an inventory of arbitrarily chosen symbols, accompanied by a group of rules of composition” of the codified units, and on the other hand from the theory of linguistic communication that wanted to “explore the opposition code/message (Jakobson): which is merely a new formulation of the Saussurian dichotomy” (Greimas and Courtés, 1979:39). From this perspective, the alphabet may be considered a code. Decoding a sign is above all relating it to the system and extracting from it the rules that allow it to rebuild a message. In order to have a code, a connection between the two systems is necessary. The system is stationary, identifiable with the qualities that define it as a system in which the observer is an exogenous variable (disturbance of the system).
The code that the information theory is concerned with a monoplanar system, as such a system can be defined not as a code but as a system, that is, a sub-code (cf. Eco 1975). Mathematical or musical systems that Hjelmslev would have called symbolic, lacking in content and therefore monoplanar, hide a possibility of significant correlation, on the basis of expectations and satisfaction. These games depend on intertextual hyper-codification of pre-existing “guides” (Eco, 1975, 2. 14.13, Eco 1979). Music is a code: all the elements of a composition (heights, intensities, tones, etc.) are related to each other; but they do not mean nor do they possess the secondary quality (which allows verbal language not only to speak of its own words that constitute it or of other sign systems, but also sentences that refuse denotation as well as representation – a lie, a periphrasis -, or even use sentences in a meaning not previously known by the linguistic community. “Code is understood to be a convention that establishes a modality of correlation between the elements having one or more systems assumed as an expression plane and the elements absent in another system (or more systems subsequently correlated with the first) assumed as a content plane, also establishing the rules of combination between the elements of the expressive system so that they are in condition to correspond to the combinations that it is hoped to express in the plan of the content” (Eco, 1976: 33-34). Eco (1970: 38-40) makes a classification that includes:
- perceptive codes: conditions of sufficient perception
- Recognition codes (of objects)
- Transmission codes (photographic, v.g.)
- tonal codes: optional variants in harmony of forms
- iconic codes: figures (geometrical, gestalten), signs (lexical elements), semes (iconic utterance: it is the image of what is understood)
- iconographic codes: the passage of iconic to the cultural seme (ex. from horse to Pegasus.
- codes of sensibility and taste: connotations taken from the semes of the preceding codes.
- rhetorical codes: organised in figures, in argumentative assumptions and complex arguments.
- stylistic codes: of an author, of a time, of a gender.
- codes of the unconscious: in relation to the operational rules of psychoanalysis.
In cryptology, a code is a system of rules that allows the transcription a certain (encrypted) message by means of a series of substitutions, so that, through them, a receiver that knows the substitution rule is capable of obtaining again the (clear) original message. A typical example is the anagram Roma (Rome in Portuguese) becomes Amor (love in Portuguese) or segreto (secret) which becomes etgorse. The Morse alphabet is also a cipher or code in the precise sense. The notion of code is of a very clear application as in the case of a bank note or of a word: there are conventions that allow us to associate a certain value to the expression /100 Euros/. This transfer of something to something else is conventional. Otherwise, it is a value that varies, whether we are referring to the Euro, Swiss franc or to the dollar. Depending on the group of regulated conventions it also refers /stomach ache/ to a medical condition and not to a mathematical operation. To sum up, code is the association of two systems of a different nature: a signified system and a significant system. There is only a code when two systems are related. Therefore, the opposition of the colour /red/ vs. /green/ in the road code corresponds to the conceptual opposition “passage prohibited” vs. “passage allowed”. It is obvious that /red/ is not naturally the opposite of /green/: in another context, it could be opposed to /white/, to /yellow/ etc., just as we could oppose /carmine red/ to /dark red/, as is the case in philately. In the code of La Dame aux Camélias, it is /white/ that opposes /red/ in a connection with the system “forbidden relationships” vs. “allowed relationships”. A basic code contains at least four units. For example: a walking cane for the blind, even though it is one of the most basic examples we can think of, is made up of four units: on the one hand the significant /white cane/ opposes to the rest (/canes not white/ and /the absence of any cane/), on the other hand this opposition of significant refers to an opposition of “blind” vs. “not blind” meanings.
Transcodification is a transformation that the same code undergoes when passing from one channel to the next. A transcodification allows the same meaning to pass through substances of different expression; for example, for language, the substances of sound and graphics. Two functions are attributed to this operation: optimizing the functioning of the channels and increasing the level of redundancy of the utterances. This is the case of the indications provided to boats when entering a channel (the lighthouses, the traffic lights, the Morse code) or the signs of writing to be read by sight, that can be, in the case of blindness, objects of a tactile transposition – which is Braille. It is the case of the driver that can call attention to himself by making use of the headlights or the horn, or of the two signs at the same time to ensure that his message gets through.
The operation of naturalised codes reveals not the transparency and “naturalness” of language but the depth of habit and the “quasi-universality” of the codes in use. These codes produce apparently “natural” recognitions. Each culture tends to impose, with different levels of enclosure, its classifications of the political, social and cultural world. These classifications constitute the dominant cultural order, even if it is not univocal or unchallenged. The domains of the “preferential” meanings are embedded in and contain the social system as a group of meanings, practices and beliefs. There is no zero level of language. What we call “distortions” or “misunderstandings” happen due to the lack of equivalence between two sides of the communicative exchange. To clarify a “misunderstanding” at the connotative level, we have to make, through the codes, reference to the orders of social life, political and economical power.