A protected blister package (50) assembled by a pharmacist for a patient has the correctness of its assembly confirmed by checking the correct correlation of three binary codes (17) respectively appearing on three components of the package. The codes are intended to provide information relating to the identity of the patient and the nature and quantity of prescribed medication doses in the blisters of the package. The first component comprises a blister sheet (58) loaded with the prescribed medication doses； the second component comprises a backing sheet (57) sealing the medication doses in the cavities of the package blisters； and the third component comprises a protective card (51) having fold lines (52,53 and 54) enabling it to be folded around the blister package (50) after it has been attached to the card. Prior to assembly of the blister package two of the binary codes (17) are printed on the backing sheet (57) and the third binary code is printed on the card. The three codes are printed at the same time to ensure that they are identical. During assembly of the package a portion of the backing sheet bearing one of its two codes is transferred to a predetermined position on the blister sheet. Correct horizontal positioning of the blister package (50) in the card achieved by lining up the left hand edge of the package with the fold line (52) and correct vertical positioning of the package is achieved by lining up the set of blocks (56) on the package with the set of blocks (55) on the protective card (51) After assembly of the protected blister package the three binary codes (17) are scanned to check that they are identical. If identity of the three codes is confirmed the package has been correctly assembled.
