(no version information, might be only in CVS)
DOMCharacterData->substringData() -- Extracts a range of data from the nodeReturns the specified substring.
The specified substring. If the sum of offset and count exceeds the length, then all 16-bit units to the end of the data are returned.
Raised if offset is negative or greater than the number of 16-bit units in data, or if count is negative.