The Marks guide is also a little bit different from the other guides. Indeed, as soon as you create one, virtual Marks in shape of a "+" appear.

Marks will not help you drawn straight or parallel lines, but they will be useful to place a text at specific intervals or regularly dispose a brush on screen.

You then have access to all of its options in the Guidelines panel.

As for the other guides, the first options (Eye, Snap, Transparency) have the same utility and parameters.

The Margin option (set to 16 by default) will magnetize your cursor at 16 pixels from your Marks guide. It is possible to change this parameter with the mini-elevator on the right or with the numeric field.

The Point X and Point Y options will allow you to create more Marks (by default, 5 in width and 5 in height, so 25 marks).

It is also possible to change these parameters with the mini-elevators on the right or with the numeric fields.

Here, there are 10x10 = 100 marks to place the text

The Edit option is also not active for the Marks guide, you will need to use the panel's parameters.

The Assist function also does not exist for the Marks guide, you need to keep the snap active for the Marks to be useful.