I have done xql.dtd -> xql.rnc transform, since it is relatively small, I am listing it below. This was done using James Clark's Trang.
# =============================================================
# XQL query file definition
# =============================================================
# Query Set
# SQL query set
queryset =
element queryset {
attlist.queryset, rdbms?, (fullquery | partialquery)*
}
attlist.queryset &= empty
# RDBMS
# Relational Database Management System
rdbms = element rdbms { attlist.rdbms, type, version }
attlist.rdbms &= empty
# Database Type
# RDBMS type e.g. oracle or postgresql
type = element type { attlist.type, text }
attlist.type &= empty
# Database Version
# RDBMS version e.g. 7.1
version = element version { attlist.version, text }
attlist.version &= empty
# Fullquery
# Full SQL query
fullquery = element fullquery { attlist.fullquery, querytext }
# name Query name
attlist.fullquery &= attribute name { text }
# Partialquery
# Partial SQL query
partialquery = element partialquery { attlist.partialquery, querytext }
# name Query name
attlist.partialquery &= attribute name { text }
# Querytext
# SQL query text
querytext = element querytext { attlist.querytext, text }
attlist.querytext &= empty
