Certificate of purity for the sacrifice of a calf
In the traditional Egyptian cult, calves were sacrificed within the enclosure of the temples; most conspicuous in this respect is the temple of the crocodile god in Soknopaiou Nesos. The procedure, already described by Herodotus (2.38), remained effective till the late II CE, when the corresponding regulation was adapted [9006 135-136 CE, Soknopaiou Nesos]. The calf to be sacrificed had to be completely white: it was examined for any black hair and, if it fit the requirement of purity, a seal was attached to its horns by the priest (ἱερομοσχοσφραγιστής ‘sealer of sacred calves’).
A certificate of purity was then issued; in addition to the certificate, see  the certificate and  the tax receipt: both documents are dated to the same day in 148 CE and relate to the sacrifice of the same calf, [P.Louvre I : 186-189; Schubert 2004 : 297-298].Most certificates originate from the temple of Soknopaiou Nesos, on the northern shore of Lake Moeris; examples in this description are from there unless otherwise stated.
In their formal structure, these certificates have a [date@start], thus signalling their official character [e.g. 13879 149 CE; 13375 210-211, Polydeukia]. This is followed by a declaration of the priest (in the first person), stating that he has examined the animal [31938 III CE]: he indicates the quantity of calves (a single animal in all preserved certificates), the location, and the name of the applicant offering the sacrifice. The certificate ends with a statement that a seal of purity has been affixed. In some cases a short note in Egyptian demotic script summarizes the content [13878 (see also for the demotic 13878, 13879)].
One case also attests the existence of a less formal structure [15062 184 CE], by which the priest makes a direct statement of having examined and sealed a calf, indicates the place and name of applicant, and declares the calf pure. There is a short [date@end], which underlines the informal character of this certificate.
Only two certificates are fully preserved [13879; 15062], but it is possible to reconstruct the overall dimensions of other fragmentary documents: they all consist of small squarish slips of papyrus [13878 (H. 9 x W. 9cm)]. The fibres are either horizontal [13878; 13879; 47261 148-149 CE] or vertical . Presumably, many papyrus slips were cut off a roll and stored in advance of sacrifices to be performed.
Where images are available, the certificates are all written in one block of text, with narrow margins, by fast and proficient scribes [15062; 13878; 13879; 47261]. Following the practice found also in tax receipts of similar format, the date placed at the beginning of the certificate displays an ἔτους with an oversized epsilon [13878; 13879].