Subsets are files storing sets of elements (the default extension of subset files is sub). Each element is stored as a four-byte element number. This way, subset file size in bytes is four times the number of elements in the subset. The same subset files can be used by different collections, but such use is meaningful only if the collections have the same numbering of elements (e.g. if these are copies of the same original collection).

Creating subsets

To create a subset use one of the following options:

• Subset : Save all on the browser menu saves the contents of the browser in a subset file (e.g. this option used on the browser opened with View : Memorized will create a subset with all memorized elements)
• Subset : Save selection on the browser menu saves all selected elements in the browser. Selections are made by clicking the leftmost browser column or with subset operations such as Subset : Select browser range, etc.
• Tools : Save as subset on the contents menu saves a contents branch in a subset file
• Child on the browser menu creates a sub-browser with all memorized, pending, dismissed or selected elements from the current browser. The new child browser can be used again in creating new subsets with Subset : Save all or Subset : Save selection as above 

Some subset files are created automatically for you. You can view them with View : Subset. For example: last_browser (subset with all elements displayed in the last opened browser), searched (subset with all elements found with the last Ctrl+F search), last_child (subset with elements extracted with the last Child operation in the browser), tasklist (subset will all tasks extracted with Tools : Open in browser on the tasklist manager menu), etc.

Note that subset operations in registries in conjunction with Browse current and Browse all are also useful here. For example: search for a given substring and choose Browse all (in the registry). You will create a browser with all elements using the found texts. This browser can also be saved in a subset file (Subset : Save all)

Using subsets

Subsets can be used in a number of ways. Here are only a few of a hundred examples:

• View : Subset opens a given subset file in the browser
• Process browser : Learning : Learn (Ctrl+Alt+L) on the browser menu makes it possible to make repetitions on a subset of elements
• Process browser : Learning : Review on the browser menu makes it possible to execute repetitions on the whole subset. Elements that are not outstanding will be subject to mid-interval repetition. Only dismissed elements will not be processed
• Process browser : Learning : Postpone (Ctrl+Alt+P) on the browser menu postpones outstanding repetitions in a subset of elements
• Tools : Transfer on the browser menu makes it possible to transfer the subset of element to another collection
• Tools : Export Q&A text on the browser menu makes it possible to export a subset of elements as a text file of questions and answers
• browser sorting options help you review a subset of elements with increasing intervals, difficulty, memory lapses, etc.
• Tools : Match to subset on the registry menu displays all registry members that are in use by the elements of a given subset