"ij" is usually sorted between "ij" and "ik" by Dutch dictionaries. The odd exception (even for Dutch speakers it seams odd) are phonebooks, because for histori

"ij" is usually sorted between "ij" and "ik" by Dutch dictionaries. The odd exception (even for Dutch speakers it seams odd) are phonebooks, because for historic reasons the surname of family members is sometimes written with "y" and sometimes with "ij". Titlecase (IJzer) is not really a problem, because there are no loan words that start with "ij" (like hijack). Very, very rarely "ij" is treated as a ligature, and counted as one letter. So, for the most part you should follow the English sorting rules, and you need one exception for handeling title case. Unicode contains a ligature "ij", which should basically not be used.