In incremental reading, you always need to quickly recover the context of a question or a piece of text. The easiest way to recover context quickly is via references. In earlier versions of SuperMemo, you would choose a piece of text, e.g. the title of an article, and mark it as reference (e.g. as title reference). This reference would propagate from element to element as you produced extracts and cloze deletions. With all child elements produced from a given text marked with references, you would never need to worry about losing the context of the question.
cannot be answered without the context. However, the following question is already easier to understand:
To speed up learning, in the Incremental reading process, the above question should naturally be replaced with:
As of SuperMemo 2008, references are not stored in HTML files that hold your articles but in a reference registry (i.e. in a separate database). The reference registry does not hold the text of references either. All reference texts are held in the text registry and are available for global text searches. In earlier versions of SuperMemo, each text would keep its own copy of references. In SuperMemo 2008 and later, elements keep only pointers to reference registry, which in turn keeps pointers to individual text fields in the text registry. As a result, many elements can hold the same reference, and many references can hold the same text. This results in a significant saving in space in your collection. More importantly, you can update the reference in a single element and see the change show in all elements using the same reference. This way, you do not need to waste time on search&replace to correct a single misspelling or reference inaccuracy that propagated to many elements.
Important! Do not add your own non-reference texts below the horizontal bar marking the reference area. All reference field area is owned by SuperMemo. Any modifications to that area will be treated as changes to reference fields. Changes that do not conform with reference field formatting will be discarded without warning.
In the picture above, an extract from an article on sleep and dreaming is presented. Blue marks an extract produced from the presented text. Yellow marks the search string (i.e. GABAergic REM-on neurons) that was used in Search : Find elements (Ctrl+F) to find all the elements (including this one) containing the string. Pink marks the reference area (consisting of the Title, Author, Date, and Source fields), which will propagate to all children elements (extracts and clozes) generated from this element.
My topics with old-style references get automatically converted and new-style references are generated. However, sometimes that process is incomplete. Some of my reference fields enter the registry, while others remain in the body of the topic.
The body of the topic is scanned for old-style references only if references are empty. Once there is a reference in the reference registry, only changes to the reference portion of the topic are detected. If you want all your old reference fields to be re-considered again, copy them to the reference part of the article (anywhere inside the pinky area under the horizontal bar). They will be scanned, deleted, converted and reformatted as a new reference.
My topics with old-style references get automatically converted and new-style references are generated. However, sometimes this does not happen at all.
For old references to be recognized, they have to be enclosed in <SuperMemoReference> tag. Those tags were not used in older SuperMemos. Those very old references will not be automatically removed; however, they should always generate the correct reference fields for the reference registry.