MacVector uses CDS features extensively in many areas. If you know the coding region, then it’s very useful to have that annotated to your sequence. For example you can display a CDS feature as its translation directly under the sequence in the Editor tab. You can also display the translation of a feature in the Map tab, instead of a graphical symbol, when there is sufficient space (for example when zoomed to residue). By default this is enabled for certain features, e.g. CDS features, genes, but it is controlled from the Symbol Editor and can be turned on/off for most features.
For example, if this is enabled for a CDS feature when zoomed to residue the amino acid will be shown.