diff --git a/service/ptos/head/arch/amd64/vas.h b/service/ptos/head/arch/amd64/vas.h
new file mode 100644
index 0000000..0f59a43
--- /dev/null
+++ b/service/ptos/head/arch/amd64/vas.h
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: AMD64 virtual address space
+ * Author:      Chloe M.
+ */
+
+#ifndef _MACHINE_VAS_H_
+#define _MACHINE_VAS_H_ 1
+
+#include <ptdef.h>
+
+/*
+ * Virtual address space for AMD64 processors
+ *
+ * @Cr3:  Control register 3 value
+ */
+typedef struct {
+    UQUAD Cr3;
+} MMU_VAS;
+
+#endif  /* !_MACHINE_VAS_H_ */
diff --git a/service/ptos/head/hal/vas.h b/service/ptos/head/hal/vas.h
new file mode 100644
index 0000000..f634ba6
--- /dev/null
+++ b/service/ptos/head/hal/vas.h
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: Platform VAS HAL interface
+ * Author:      Chloe M.
+ */
+
+#ifndef _HAL_VAS_H_
+#define _HAL_VAS_H_ 1
+
+/*
+ * This header must define an MMU_VAS structure per
+ * architecture.
+ */
+#include <machine/vas.h>
+
+#endif  /* !_HAL_VAS_H_ */