This payoff depends on two strikes K and K' with K' > K, whereby the first strike K sets the lower trigger as well as the payoff amount, whereas the second strike K' sets the upper trigger only.
The payoff amount equals C and is paid only if x lies between K and K'.
Supershare sometimes is also called "Superfund", which can lead to ambiguity.
Within QuantLib the terms supershare and superfund are used consistently according to the definitions in Bloomberg OVX function's help pages.
The formal definition is as follows:
x is transformed into C if K <= x < K' and 0 otherwise where K and K' are constants defined in the contract specification.