15. A non-transitory computer readable medium containing computer executable instructions that, when executed by one or more processors of a computer, allow said one of more processors to execute the following steps: providing at least a closed extract stored in said computer, wherein said closed extract is a data set that contains references to the words of a language sample of a target language, and optionally also contains references to additional words or localizers, wherein a localizer is a string of symbols, said string of symbols not being a word in said target language, providing at least two relations stored in said computer, wherein a relation is a data set that comprises the information required to perform one or more modifications upon said closed extract, activating at least one of said relations, wherein said activation applies to said closed extract the one or more modification that are associated to said one relation, said application producing a second closed extract, this second closed extract being a modified closed extract, filtering at least one of said closed extracts to create an open extract, said open extract being a text fragment in the target language optionally containing in addition one or more localizers, wherein an open extract that is produced after filtering a modified closed extract is a modified version of said sample, presenting said open extract in said display, wherein said modified version differs from said sample in one of the ways included in the following plurality of ways: it contains additional words, or it contains some of the same words in different order, or it contains localizers, so that presenting one or more modified versions helps the user to understand said sample, and said method provides an aid to the user for understanding said sample.
17. A non-transitory computer readable medium as claimed in claim 15 , wherein said computer executable instructions allow said one or more processor to further perform the following steps: providing a list of modification types, wherein a modification type is a data entity that defines what modification would be performed upon one or more fragments of closed extracts, providing at least one relational scheme, wherein a relational scheme is a data set that performs as a template, said relational scheme containing at least two parts, the first one of said parts defining one of said modification types, and the second one of said parts being a variable that can be assigned to one fragment of said closed extracts, presenting said relational scheme in said display, detecting a user action, said action assigning a specific fragment of said closed extract to said variable, and creating a new relation, said creation assigning said relational scheme and said fragment to said relation, so that this steps provides an aid to the user to create new relations.