RtlNextUnicodePrefix - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers
#ifndef _NTRTL_H

NTSYSAPI
PUNICODE_PREFIX_TABLE_ENTRY
NTAPI
RtlNextUnicodePrefix(
    _In_ PUNICODE_PREFIX_TABLE PrefixTable,
    _In_ BOOLEAN Restart
    );

#endif

View code on GitHub

This function is documented in Windows Driver Kit.