• Reference Guide


Determines, whether the specified l-value lval or reference ref (the type Dref) refers to a data item that can potentially exist. The function returns TRUE, if the data item exists, or if does not exist, because it is optional, or does not exist, because the reference passes over a sequence containing too few elements (but by inserting further elements the reference would identify a valid data item). In the other cases, the function returns FALSE.

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