Only one of the attributes 'target' and 'cRef' may be supplied. Only one of the attributes 'target' and 'cRef' may be supplied. If the 'target' attribute is used, the relatedItem element must be empty A relatedItem element should have either a 'target' attribute or a child element to indicate the related bibliographic item You may not nest one s element within another: use seg instead A feature value cannot contain both text and element content A feature value can contain only one child element You may not supply both @target and @targets You must supply either @target or @targets You must supply at least two values for @target You may not supply both @target and @targets You must supply either @target or @targets You must supply at least two values for @target You may not supply both @target and @targets You must supply either @target or @targets You must supply at least two values for @target Width element may appear once only Height element may appear once only Depth element may appear once only You must supply either a locator of some type or a name Only one <lem> element may appear within a single apparatus entry, whether it appears outside a <rdgGrp> element or within it. The spanTo= attribute of is required. The spanTo= attribute of is required. The spanTo= attribute of is required. Only one of the attributes 'active' and 'mutual' may be supplied the attribute 'passive' may be supplied only if the attribute 'active' is supplied