Replys like « 5 cm » or « 50 mm » will be accepted and analyzed as equivalent. It is the same with « 1 h 20 min » and « 4800e3 ms ». The mechanism which is used is the most robust, it relies on dimensional analysis.
WIMS knows how to analyze expressions like the equation of the synthesis of water: « H2 + 1/2 O2 ----> H2O », parse them, recognize if they are equilibrated, output correctly typeset images like $H_2\,+\,\frac{1}{2}O_2\longrightarrow\,H_2O$