The Gap comma code, normally G, allows you to suspend the drawing of a line feature for a given segment and should be assigned to the point that immediately precedes the required gap. This may happen where there is a gap in a hedge, a fence or a wall. The example below shows a gapped hedge and you should note that the calculations for curve fitting are carried out through the gap as though the segment was there.
The attribute check button Alternate Segments allows you to produce a line feature that only displays alternate segments. Examples of this would be a road marking that does not have standard lengths such as the lines of road hatching used for carriageway separation.