<?tbcabove>

1. Use without parameters to terminate a <?tbcbelow> command and return to the default behavior of stacking cells in a boxed row above existing cells.

2. Use with parameters to modify the default vertical placing of a cell, rather than having it calculated automatically.

When working out how to stack cells within a boxed row, by default PTC ALD examines all other cells in the row that span the same columns that the current cell spans, and then sits the new cell above the tallest one. The first, last option allows you to specify an alternative range of cells that PTC ALD should examine for height. Note that in this situation the cell still sits in the columns designated by <?tbcstrt>, it is merely its height that is extracted from this range.

Using <?tbcabove> with parameters overrides PTC ALD automatic behaviour and can give odd results, including forcing cells to clash into one another; particularly when using a negative cellnum.

[no parameter]	Return to default setting of cells stacking above only.
first	The number of the first cell in an alternative range that PTC ALD should examine to find the highest cell.
last	The number of the last cell in the range: if last is not specified its value defaults to that of first.
-cellnum	The number of a particular cell within the boxed that the current cell should sit above. The cells in the boxed row are counted from 1 until cellnum is reached and then the cell is placed. The minus signifies that this is a cell number rather than a column number.

In the example below, the cells in red have been modified using <?tbcabove> and <?tbcbelow>: cell 6 has been forced to the same height as 7 and subsequently cells 8 and 9 have been instructed to fill in the remaining gaps.