4 In accordance with the R.O.C. Patent Act and its enforcement rules, which of the following is correct?
(A) An dependent claim should state the designation of the subject matter as claimed and the essential technical features of the invention that the applicant regards as his/her invention.
(B) A dependent claim may only depend on the preceding dependent or independent claim(s). However, direct or indirect dependence is not allowed among multiple dependent claims.
(C) The technical features of the claim(s) may refer to the corresponding reference sign(s) in the drawing(s), and the reference sign(s) should follow the corresponding technical features and be placed in parentheses; the reference sign(s) may serve to limit the interpretation of the claim(s).
(D) The claim(s) may contain the chemical or mathematical formulae and drawing(s).