Why not bother to divide sanahtlig's post so that the question is right above the answer, my god that's a pain to read since you need to go back up for every paragraph to check the question before you come back for the answer.

Anyway.
mainstay
/ˈmeɪnsteɪ/
noun
a stay which extends from the maintop to the foot of the foremast of a sailing ship.
someone or something on which something else is based or relies.
What.

Would you mind explain what you meant by "mainstay content"?