only one while the vocabulary modules are shown as part of the server 3 they could also be located on the distributed network the vocabulary modules 8 and 9 communicate through bidirectional connections 13 and 14 with lexicons 15 and 16 or more of them as indicated by dotted line 17 however it is also possible to have only one lexicon the lexicons are preferably implemented as databases associating terms with resources on the web they hold database tuples for mapping terms into tokens as will be explained below wherein each tuple usually contains a term a token type e g class property instance constraint a uniform resource identifier uri a relevance factor indicating the degree of correlation between the term and the token the purpose of the vocabulary modules 8 and 9 is to adapt the output of the parser 7 to the structure and query language of the lexicons 15 and 16 parser and vocabulary modules communicate through well defined interfaces e g via http where the output of the vocabulary modules can be expressed in an appropriate format e g as an xml encoded string that way the token retrieval process is independent of the underlying database management system in fig1 dashed line 18 symbolically represents the separation between the server 3 and a distributed network the network can e g be the world wide web on the.