Letter case is often prescribed by the grammar of a language or by the conventions of a particular discipline. In orthography, the uppercase is primarily reserved for special purposes, such as the first letter of a sentence or of a proper noun, which makes the lowercase the more common variant in text. In mathematics, letter case may indicate the relationship between objects with uppercase letters often representing "superior" objects (e.g. X could be a set containing the generic member x). Engineering design drawings are typically labelled entirely in upper-case letters, which are easier to distinguish than lowercase, especially when space restrictions require that the lettering be small.
What is often prescribed by the grammar of a language or by conventions of a particular discipline? Which kind of purpose is uppercase reserved for in orthography? Which is the most common variant of case in text? Engineering design drawings typically utiilze which case of letter in labeling? Why are uppercase letters preferred often times when space is restricted?