Evidence of monthly earned income and travel expenses
11.—(1)  No claim submitted by a witness in respect of —
(a)his monthly earned income; or
(b)any travel expenses referred to in regulation 7,
shall be considered unless such witness produces to the authorising officer together with his claim such evidence of his monthly earned income or travel expenses as the authorising officer may require.
(2)  If no such evidence is available, the allowances for such witness shall be fixed by the authorising officer at his discretion.