Lojban doesn't use lower-case (small) letters and upper-case (capital) letters in the same way that English does; sentences do not begin with an upper-case letter, nor do names. However, upper-case letters are used in Lojban to mark irregular stress within cmevla, thus:

It would require far too many cmavo to assign one for each upper-case and one for each lower-case lerfu, so instead we have two special cmavo ga'e and to'a representing upper case and lower case respectively. They belong to the same selma'o as the basic lerfu words, namely BY, and they may be freely interspersed with them.

The effect of ga'e is to change the interpretation of all lerfu words following it to be the upper-case version of the lerfu. An occurrence of to'a causes the interpretation to revert to lower case. Thus, ga'e .abu means not “a” but “A”, and Ivan's name may be spelled out thus:

The cmavo and compound cmavo of this type will be called “shift words”.

How long does a shift word last? Theoretically, until the next shift word that contradicts it or until the end of text. In practice, it is common to presume that a shift word is only in effect until the next word other than a lerfu word is found.

It is often convenient to shift just a single letter to upper case. The cmavo tau, of selma'o LAU, is useful for the purpose. A LAU cmavo must always be immediately followed by a BY cmavo or its equivalent: the combination is grammatically equivalent to a single BY. (See Section 17.14 for details.)

A likely use of tau is in the internationally standardized symbols for the chemical elements. Each element is represented using either a single upper-case lerfu or one upper-case lerfu followed by one lower-case lerfu:

If a shift to upper-case is in effect when tau appears, it shifts the next lerfu word only to lower case, reversing its usual effect.