4. There may be paid into a client account —
(a)
trust money;
(b)
such money belonging to the solicitor as may be necessary for the purpose of opening or maintaining the account;
(c)
money to replace any sum which for any reason may have been drawn from the account in contravention of rule 8(2); and
(d)
money received by the solicitor, which under rule 5 he is entitled to split but which he does not split.