In the double-letter scheme, this was not generally possible once designations had been assigned in a subsequent year. The scheme used to get round this problem was rather clumsy and used a designation consisting of the year and a lower-case letter in a manner similar to the old provisional-designation scheme for comets. For example, (note that there is a space between the year and the letter to distinguish this designation from the old-style comet designation 1915a, Mellish's first comet of 1915), 1917 b. In 1914 designations of the form year plus Greek letter were used in addition. Temporary designations are custom designation given by an observer or discovering observatory prior to the assignment of a provisional designation by the MPC. These intricate designations were used prior to the Digital Age, when communication was slow or even impossible (e.g. during WWI). The listed temporary designations by observatory/observer use uppercase and lowercase letters (codice_11, codice_12), digits, numbers and years, as well Roman numerals (codice_13) and Greek letters (codice_14). The system used for comets was complex previous to 1995. Originally, the year was followed by a space and then a Roman numeral (indicating the sequence of discovery) in most cases, but difficulties always arose when an object needed to be placed between previous discoveries. For example, after Comet 1881 III and Comet 1881 IV might be reported, an object discovered in between the discovery dates but reported much later couldn't be designated "Comet 1881 III½". More commonly comets were known by the discoverer's name and the year. An alternate scheme also listed comets in order of time of perihelion passage, using lower-case letters; thus "Comet Faye" (modern designation 4P/Faye) was both Comet 1881 I (first comet to pass perihelion in 1881) and Comet 1880c (third comet to be discovered in 1880). The system since 1995 is similar to the provisional designation of minor planets. For comets, the provisional designation consists of the year of discovery, a space, ONE letter (unlike the minor planets with two) indicating the half-month of discovery within that year (A=first half of January, B=second half of January, etc. skipping I (to avoid confusion with the number 1 or the numeral I) and not reaching Z), and finally a number (not subscripted as with minor planets), indicating the sequence of discovery within the half-month.