Schema versioning is an indispensable feature for applications using temporal databases and requiring an entire history of data and schema. oXSchema [7] is an infrastructure for constructing and validating temporal XML documents, but any explicit support for XML schema versioning is offered. A oXSchema schema is composed of a conventional XML Schema document annotated with physical and logical annotations. All components of a oXSchema schema can change over time to reflect changes in user requirements or in reference world of the database. In a previous work [10], we deal with versioning of logical and physical annotations. In this work, we study versioning of oXSchema conventional schema: we propose a complete set of low-level primitives for changing such a schema and define their operational semantics.