Introduction
The process of creating unlimited text entry fields was crucial to implementing an exposure estimation system we developed for managing a large collection of task exposure information. In addition to entering all of the actual exposure data, the investigators wanted to be able to record extensive comments about many of the different exposure components. Microsoft Word documents already existed which contained some task comments, other comments existed in Excel spreadsheets, and others would need to be entered into the system manually. Another design criteria was to be able to enter any amount of textual information into the comment fields. Placing a subjective limit of 10, 20 or even 100 lines of text was not acceptable because some documents were several hundred lines in length.
We explored the feasibility of using SAS datasets to store the comment fields, but this approach had several significant weaknesses. One problem with using standard SAS character variables was the fact that each character variable would have to be defined in advance. Another disadvantage was the amount of wasted space that would occur with dozens or hundreds of predefined character variables, each of which would need to be 100 or more bytes in length. The major reason we discounted this approach was the fact that we needed to have the ability to enter an unlimited amount of text in each comment field. This design criteria forced us to come up with a novel solution for implementing unlimited text entry fields.