How can I create a zero-length point feature between two DNA bases?
In this example we add a point feature to mark an cDNA splice site.
View the Sequence

Near the beginning of this cDNA sequence, a single intron was spliced out. Our goal is to mark this intron splice site as a zero-length point feature.
Mark the Feature Insertion Point

We know the intron was located between bases 10 and 11. Click to place the cursor at this position.
Add a Point Feature

To add a point feature, click Features → Add Feature... .

Type a feature name, select a feature color, and add a note if desired. Then click OK.
View the Point Feature

A point feature now marks the intron splice site. When the point feature is selected, it is marked in the DNA sequence with a blue line.

To deselect the point feature, click elsewhere in the window.

In Map view, the point feature is annotated as a bar in the DNA line.

In Features view, the point feature is listed as a zero-length feature between two bases.
Export the Sequence and Feature Annotations

To export the sequence and feature annotations to standard GenBank format, click File → Export → DNA... . Type the file name, verify the file format, then click Save.

The exported GenBank file lists the point feature.