Comment by ajb

Yes, you are allowed to do that. You do occasionally run into someone who checks for gaps - someone asked me about a gap 20 years ago recently. Although I don't know if they actually cared or just had engineer's checking brain engaged. If they expect you to be that vanilla you may not want to work with them - remember the point of a CV, just like the rest of the process, is to maximise the chance of getting a placement you match, not just maximise the chance of getting to the next step. Causing people you wouldn't want to work with to filter you out is a plus.