When it comes to synonyms for the phrase "is mark," there are several options to choose from. Some possible alternatives might include "represents," "signifies," "indicates," or "demonstrates." Other options could include "denotes," "symbolizes," "suggests," or "implies." In each case, these words are all working to convey the same basic meaning as "is mark," which is to indicate or suggest what something means or represents. Ultimately, the choice between these different synonyms will depend on the specific context and the writer's intended tone and voice.