The Tab Options is located on the Editor tab in Preferences.

Use Tab Characters

If checked, Tab characters will be used when the tab key is pressed on the keyboard. If unchecked (blank) normal spaces are used instead, just like when you press the spacebar on the keyboard.

Smart Tab

If checked, the cursor will do one of the following;

• advance to the same column (vertical alignment) as the beginning of the line of text above it, or
• advance to the beginning of the next word in the line of text above the current line [see note], or
• advance to the end of the line of text above the current line [see note], or
• advance by the number of spaces/tab width specified in the Tab Stop setting.

[note] items 2 and 3 are progressive. That is, if multiple lines are above the current line and the higher lines are longer, once the cursor reaches the end of the first line above it, it will "look" at the next highest line and so on until it has cleared all lines above it.

Optimal Fill

When Optimal Fill, Use Tab Characters and Smart Tab are checked, the cursor advances per the Smart Tab setting mentioned above. Tab characters are used where possible based on the Tab Stop setting value. If a tab character will not fit, spaces are used.

If Optimal Fill is unchecked and the Use Tab Characters and Smart Tab are both checked, spaces are used instead of tab characters.

Tab Stop

The number of spaces (columns) to advance when the Tab key is pressed. If "Use Tab Characters" is checked, this is the length (size) of the tab character.

The Smart Tab setting overrides this setting until the cursor clears all lines above the current line. Afterwards, the cursor advances based on the Tab Stop setting.

Columns

A number representing the column the cursor will advance to when the tab key is pressed. To specify more than one column stop, separate the column numbers with a space, like so: 10 20 30. The cursor will first advance to column 10, then column 20, then column 30.

Once the cursor has progressed passed any defined column stops the cursor will advance by the number of spaces (tab width) specified in the "Tab Stop" field.

It is possible to use characters to separate the numbers such as a comma or semi-colon, but it's not necessary

The Smart Tab setting will override the Columns settings if there is a conflict.