When a set is incomplete, it is better to leave blank spaces for the missing stamps. But if some of the missing stamps are very rare and the collector thinks that it is not possible to have that in near future because of his pocket, it is better not to leave space for such stamps. Spaces must be left only for those stamps which the collector hopes to obtain in the near future- Writing up is the embellishment of a page or collection by the addition of hand or typewritten data concerning the description of the stamps displayed. But the written material is entirely upto the collector. He may also write date of issue, reason or occasion of issue, if commemorative or unusual, design, paper, printing process, perforation etc.
Some collectors make few notes on, the persons, places, or incidents shown on the stamps.
Enlarged detail, either hand drawn or reproduced otherwise, may accompany such writing up but over elaboration should be avoided at all costs. Essentials are a balanced, uncrowded arrangement, neatly hand written or typed lettering or script in black, and with all the essential facts given. In thematic collection arrangement and writeup are different from that of the country collection. In arranging thematic collection, it is not necessary to show a complete set on the same sheet. In thematics, collection is arranged on the basis of the theme depicted on the stamps e.g. in a collection on wild life, on the page showing lion's, stamps of elephants or monkeys must be avoided.