17. A method of decoding coded data of a structured document into decoded string of characters, the method comprising a step of decoding the coded data by substituting a decoded string of characters from at least one decoding dictionary for a coding index, said at least one decoding dictionary comprising entries, each entry associating a respective coding index with a decoded string of characters, the method further comprising: identifying, in said coded data to decode, and decoding, at least one item of reference information linking a string of characters of an entry in the decoding dictionary to the decoded string of characters corresponding to the coded data to decode, by matching between at least a continuous part of the decoded string of characters corresponding to the coded data to decode or the string of characters of the entry in the decoding dictionary and a continuous subpart of other string of characters; and wherein said at least one item of reference information comprises an identifier of a selected indexing dictionary from amongst a plurality of indexing dictionaries, an item of information identifying said entry identified in the selected indexing dictionary, an item of information on positioning which indicates a first character of the identified entry string of characters that matches the part or subpart of the decoded string of characters and an item of information on length of the matching part and subpart representing a number of characters of the matching part and subpart; recovering said part or subpart of the string of characters of the entry from said decoded reference information so as to form, at least partly, the decoded string of characters corresponding to the coded data to decode, wherein the decoding dictionary is distinct from the structured document, wherein the item of information identifying said indexing dictionary, the item of information identifying said entry, the item of information on positioning, and the item of length information, are distinct information items, wherein the selected indexing dictionary comprises an entry corresponding to an already decoded substring of said string of characters to be decoded, so that a subsequent substring of said string of characters to be decoded is decoded with reference to said already decoded substring, and wherein the positioning information is selected from a set comprising a first code when said part or subpart of the string of characters to be decoded corresponds to a start of the entry identified, a second code when said part or subpart of the string of characters to be decoded corresponds to an end of the entry identified, and an offset value of the position of said part or subpart of the string of characters to be decoded in the entry identified, in other cases.
17. A method of decoding coded data of a structured document into decoded string of characters, the method comprising a step of decoding the coded data by substituting a decoded string of characters from at least one decoding dictionary for a coding index, said at least one decoding dictionary comprising entries, each entry associating a respective coding index with a decoded string of characters, the method further comprising: identifying, in said coded data to decode, and decoding, at least one item of reference information linking a string of characters of an entry in the decoding dictionary to the decoded string of characters corresponding to the coded data to decode, by matching between at least a continuous part of the decoded string of characters corresponding to the coded data to decode or the string of characters of the entry in the decoding dictionary and a continuous subpart of other string of characters; and wherein said at least one item of reference information comprises an identifier of a selected indexing dictionary from amongst a plurality of indexing dictionaries, an item of information identifying said entry identified in the selected indexing dictionary, an item of information on positioning which indicates a first character of the identified entry string of characters that matches the part or subpart of the decoded string of characters and an item of information on length of the matching part and subpart representing a number of characters of the matching part and subpart; recovering said part or subpart of the string of characters of the entry from said decoded reference information so as to form, at least partly, the decoded string of characters corresponding to the coded data to decode, wherein the decoding dictionary is distinct from the structured document, wherein the item of information identifying said indexing dictionary, the item of information identifying said entry, the item of information on positioning, and the item of length information, are distinct information items, wherein the selected indexing dictionary comprises an entry corresponding to an already decoded substring of said string of characters to be decoded, so that a subsequent substring of said string of characters to be decoded is decoded with reference to said already decoded substring, and wherein the positioning information is selected from a set comprising a first code when said part or subpart of the string of characters to be decoded corresponds to a start of the entry identified, a second code when said part or subpart of the string of characters to be decoded corresponds to an end of the entry identified, and an offset value of the position of said part or subpart of the string of characters to be decoded in the entry identified, in other cases. 20. The method according to claim 17 , comprising a step of determining, in a bitstream of the coded data, an item of coded data to be decoded using at least one indication indicating the end of said item of coded data.