Multiple document displaying for viewing and editing

A machine-readable medium that provides instructions which, when executed by a machine, cause said machine to perform operations including:

• displaying a first document on a display screen;
• receiving a command to insert an enhancement point at an anchor point in the first document;
• displaying the enhancement point at the anchor point in the first document;
• receiving a command to create a first enhancement implementation at the enhancement point, the command defining a second document to be inserted into the first enhancement implementation;
• displaying the first enhancement implementation;
• receiving a command to create a second enhancement implementation at the anchor point, the command defining a third document to be inserted into the second enhancement implementation;
• and
• displaying the second implementation section, wherein the second document or the third document is displayed at the anchor point depending on whether the second document or the third document, respectively, is selected to be active.

An apparatus comprising:

• a document module configured to receive a first document, a second document and a third document from at least one machine-readable media, the second document being at least one of a replacement of part of the first document or an addition to the first document;
• the third document being at least one of a replacement of part of the second document or an addition to the second document;
• and
• a display controller configured to display, on a display, the first document, the second document and the third document in a nested enhancement hierarchy.