How can I determine if a symbol is invalid?

[bullman]

I am attempting to get historical data for several symbols. If I request a symbol that does not exist, what type of information does eSignal produce to tell me so?

In other words, if I pass a bad symbol, eSignal returns a valid handle, but does not generate any ES_OnBarsReceived, ES_OnBarsChanged, or any other messages, leaving me hanging.

How can I determine if a symbol is invalid, other than just timing out after a long wait for data (not practical).

[TGafford]

There is no way to determine if a symbol is invalid.

The eSignal application programmatically checks if a symbol meets the syntax requirements for a possible symbol. Apart from that, the eSignal application cannot tell if a symbol that meets the syntax requirements is a symbol that exists somewhere in the market.