30.13.1 What is a Text-based Table?

Keep the following examples of valid tables in mind as a reference while you read this section:

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

A table consists of a rectangular frame whose inside is divided into cells. Each cell must be at least one character wide and one character high, not counting its border lines. A cell can be subdivided into multiple rectangular cells, but cells cannot overlap.

The table frame and cell border lines are made of three special characters. These variables specify those characters:

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