Subsets are files storing collections of elements (the default extension of subset files is SUB). Each element is stored as a four-byte element number. This way, subset files size in bytes is four times the number of elements in the subset. The same subset files can be used by different knowledge systems, but such use is meaningful only if the systems have the same numbering of elements (e.g. if these are copies of the same original system).
To create a subset use one of the following options:
* Subset : Save all in browsers - save the contents of the browser in a subset file (e.g. this option used on the browser menu with View : Memorized will create a subset with all memorized elements).
* Tools : Save as subset on the Contents menu - save a Contents node in a subset file.
* Subset : Save selection in browser - save all selected elements in the browser (selecting is done by clicking the leftmost column or with subset operations such as Add, Subtract and Intersect). See Browser menu for more. As child operations in the browser change its contents, they can also be useful in creating subset files.
Note that subset operations in registries in conjunction with Feed one to browser and Feed all to browser are also useful here. For example: search for a given substring and choose Feed all to browser. You will create a browser with all elements using the founds texts. This browser can be saved in a subset file.
Subsets can be used in a number of options of which most prominent are:
* File : Export : Subset as text - exports a subset file as an element subset text file that can be imported into another knowledge system
* File : Export : Translation - exports translation of texts used in elements from a subset file
* Tools : Match to subset in registries - makes it possible to select all registry members that are in use by elements listed in a subset file. For example, by using Search and replace : Find in a registry, one can easily find strings that are used by a given element subset and contain the selected search substring.
* View : Subset - opens a given subset file in the browser.
* Tools : Random test : Subset - runs a random test of knowledge on a subset of elements.