30.13.1 What is a Text-based Table?

Look at the following examples of valid tables as a reference while you read this section:

                   +--+----+---+     +-+     +--+-----+
                   |  |    |   |     | |     |  |     |
                   +--+----+---+     +-+     |  +--+--+
                   |  |    |   |             |  |  |  |
                   +--+----+---+             +--+--+  |
                                             |     |  |
                                             +-----+--+

A table consists of a rectangular frame and the contents inside the frame. A table's cells must be at least one character wide and one character high with two adjacent cells sharing a boarder line. A cell can be subdivided into multiple rectangular cells but cannot nest or overlap.

Both the table frame and cell border lines must consist of one of three special characters. The variables that hold these characters are described below:

table-cell-vertical-char

Holds the character used for vertical lines. The default value is ‘|’.

table-cell-horizontal-char

Holds the character used for horizontal lines. The default value is ‘-’.

table-cell-intersection-char

Holds the character used at where horizontal line and vertical line meet. The default value is ‘+’.

Based on this definition, the following five tables are examples of invalid tables:

        +-----+    +-----+       +--+    +-++--+    ++
        |     |    |     |       |  |    | ||  |    ++
        | +-+ |    |     |       |  |    | ||  |
        | | | |    +--+  |    +--+--+    +-++--+
        | +-+ |    |  |  |    |  |  |    +-++--+
        |     |    |  |  |    |  |  |    | ||  |
        +-----+    +--+--+    +--+--+    +-++--+
          a           b          c          d        e

From left to right:

1. Nested cells are not allowed.
2. Overlapped cells or non-rectangular cells are not allowed.
3. The border must be rectangular.
4. Cells must have a minimum width/height of one character.
5. Same as d.