Column Ruler

DDS is a fixed-column format: a value typed one or two columns off lands in the wrong area, and often still compiles. For example, COST 7 0 meant as a 7-digit output field puts the 0 in the decimal positions instead of the usage, and the field quietly becomes a numeric field with no usage coded.

The column ruler helps spot this while editing the source by hand. It works like the fixed-format RPG ruler of the vscode-rpgle extension, and like the format line of SEU and RDi.

Turning it on

The ruler is off by default. Turn it on or off either way:

• Press Shift+F4 in a DDS display file source.
• Check Show a column ruler above the line being edited in the Source Editor section of the ⚙ Configuration panel. See Configuration.
• Run DSPF Edit: Show/Hide Column Ruler from the Command Palette.

The setting is remembered, and the checkbox in the Configuration panel follows Shift+F4.

What it shows

On the line the cursor is on:

• Above it, the DDS format line, positions 1 to 80:

  .....AAN01N02N03T.Name++++++RLen++TDpBLinPosFunctions+++++++++++++++++++++++++++

• On the line itself, each column area is outlined, and the area the cursor is in is highlighted. Hover an area to see its name and positions, e.g. Decimal positions (36-37).

Positions	Area
7	Condition And/Or
8-10, 11-13, 14-16	Indicators 1, 2 and 3
17	Name type
19-28	Name
29	Reference
30-34	Length
35	Data type
36-37	Decimal positions
38	Usage
39-41	Line
42-44	Position
45-80	Functions (keywords)

The ruler covers the line above while the cursor is on a line, and isn’t shown on comment lines (* in position 7). Areas past the end of a short line aren’t outlined, but the format line above still shows where they are.