xm:f: An f element that specifies the formula that is evaluated and compared to the cell value by the comparison method specified by gte. The formula MUST adhere to the grammar provided in Formulas, with the following restrictions:
MUST NOT use the ref-infix-operator, book-prefix, local-cell-reference, bang-reference, bang-name, array-constant, sheet-range-reference or structure-reference production rules.
MUST NOT use the A1-relative-column production rule except from the A1-absolute-column production rule, and it MUST NOT use the A1-relative-row production rule except from the A1-absolute-row production rule.
MUST NOT match the single-sheet-area production rule.
