What does 'the king' mean in this sentence?
Magna Carta restricted the king’s power and gave new rights to the barons and the people.

This is from the word definition for 'Marga Carta' in a dictionary for English learners.
Does 'the king' mean only King John, who signed it in 1215?

Question

What does 'the king' mean in this sentence?
Magna Carta restricted the king’s power and gave new rights to the barons and the people.

This is from the word definition for 'Marga Carta' in a dictionary for English learners. 
Does 'the king' mean only King John, who signed it in 1215?

Answer

An interesting question. Here 'the king' refers to whoever is king. King John signed it, but it was written to apply to all future monarchs as well.

Answer

John was king at the time so it restricted his  power but it was meant to be all kings.