Importing a file thus implies nothing more than a translation process.

- A process not too dissimilar to that of translating a text into another language, where it is often not possible to convey all the details without losing some aspects of the language, e.g. idiomatic expressions. However, the translator mostly finds a way of expressing the sense of idiomatic expression using other words.

Importing illustration data functions in a similar way. Most data can be transferred completely, although there is almost always an amount left over which contains program-specific details. This data can only be translated by conveying its "sense".

This type of translation, however, always results in some information being lost. This may mean that attributes of an object are lost during the transfer procedure. For example, a thread converted from IsoDraw into Adobe Illustrator format can only be depicted as a group of Bézier paths. It is no longer possible to set the thread depth or diameter in Adobe Illustrator in the same way as in IsoDraw.

The differences between the two programs become even more acute when an element cannot be converted properly. HPGL format, for example, contains no commands for displaying curves, meaning that each curve has to be converted into a series of short, straight-line segments.

The same naturally applies when a drawing is exported into another format. IsoDraw contains a large number of elements and attributes which are not supported in other programs. In which case, you will need to choose the "least of all evils" when converting a file.

It is possible to measure the quality of a filter by how carefully the individual attributes are converted. In many instances, just the pure geometrical data is translated. However, it is generally possible to do more. And last but not least, don't forget that the filter is not always to blame if information is lost.