In White Paper ( https://steem.io/SteemWhitePaper.pdf ) write:
"The fundamental unit of account on the Steem platform is STEEM, a crypto currency token. Steem operates on the basis of one-STEEM, one-vote. Under this model, individuals who have contributed the most to the platform, as measured by their account balance, have the most influence over how contributions are scored. Furthermore, Steem only allows members to vote with STEEM when it is committed to a multi-year vesting schedule. Under this model, members have a financial incentive to vote in a way that maximises the long term value of their STEEM."

"Steem Dollars (SMD)
Stability is an important feature of successful global economies. Without stability, individuals across the world could not have low cognitive costs while engaging in commerce and savings. Because stability is an important feature of successful economies, Steem Dollars were designed as an attempt to bring stability to the world of cryptocurrency and to the individuals who use the Steem network."

I think may be used as a symbol "SD" or "SteemDollars".