In editorial design, the Index is another graphic element, but must be submitted to a practical criterion: the reader must find easily and immediately what is looking for. Although this depends on several factors, the design object, the kind of design, to whom it is addressed. But being practical, the most important points are:
- The Total Text Extension
- The Item Length
- The Column Width
This can help to get an idea about what could be good or not. But this is always at the designer view. In fact InDesign in its Automatic Table of Contents offers all the possibilities.
Short Item – Narrow Column, both alignments are right, but the right align it's less confuse.
Long Item – Narrow Column, in narrow columns, a long text is difficult to read, the change of lines is very continuous, so the last one can get the number at the end avoiding an added effort to the reader.
Short Item – Wide Column, wide columns are not so easy in Index, the best option is not to put the entry number so far.
Long Item – Wide Column, the worst situation, better avoid. The two kind of alignments are OK, but in the right alignment the number is very far and in the left alignment it is confused with the text.
For those extreme cases the option of the underlined tabulator provides an optimal solution not only to the item itself but to the complete index.