Nested Table Data Model (NTD)
In this chapter, a new data model named the nested table data model (NTD) is proposed as a canonical model for data definition and manipulation of forms and form-based documents (here termed form documents) in computer environments. In NTD, nested tables (NTs) are used as canonical data representations. Briefly, an NT is a table with nests of columns and rows. An example of an NT PROG_SPEC is shown in Fig. 3.1. NTs are abstract representations of data in form documents such as those printed and written on paper and displayed on screen. For example, data in a sample form document shown in Fig. 3.2 are directly representable as a row in NT PROG_SPEC shown in Fig. 3.1. Fig. 3.3 illustrates the mapping between real external form documents and NTs. Generally, data in a form document can be mapped down into an NT having only one row. Thus, it would seem that we need not consider NTs having multiple rows. However, we offen have to handle a bunch of form documents based on the same form. In addition, NTs having more than one row are useful in modeling NT data handling. For these reasons, we allow NTs to have multiple rows, which makes NTD useful as an underlying data model.
KeywordsOperational Property Selection Condition Group Schema Form Document Data Manipulation
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