# How to insert long subscripts involving characters?

I tried to write METrate (where rate denotes the subscript) as $MET_rate$. But only r appears as subscript.When I tried writing it as $MET_r_a_t_e$ I get it in the correct format during compilation as expected but it throws an error "Double subscript".

Just put the subscript within curly braces. Replace $MET_rate$ by $MET_{rate}$.
• Better still, write either $\mathrm{MET}_{\mathrm{rate}}$ or $\mathit{MET}_{\mathit{rate}}$, depending on whether the variable names "MET" and "rate" should be rendered in upright or italic form. – Mico Dec 1 '15 at 6:48