You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Szlachta

Context:
In theory at least, all Polish noblemen were social equals. Also in theory, they were legal peers. Those who held 'real power' dignities were more privileged but these dignities were not hereditary. Those who held honorary dignities were higher in 'ritual' hierarchy but these dignities were also granted for a lifetime. Some tenancies became hereditary and went with both privilege and titles. Nobles who were not direct barons of the Crown but held land from other lords were only peers "de iure".

Question:
Was was unique about the dignities?

not hereditary