Some systems allow snippet placeholders to be named identifiers. Variables closely resemble variables in logic in that they are placeholders for arbitrary terms. Formatting takes place via placeholders within the format string. The alphabetic characters to the left are used as placeholders for these variables. This is customarily done by supplying a transcluded text with one or more "substitution placeholders". Empty frames hang in the Dutch Room gallery as placeholders for the missing works. In genetics, symbols began as algebraic placeholders. Other place names may be used as generic placeholders, depending on the speaker's origins. Column values are substituted for each of the named placeholders in the scenario. Like other Interlingua words, placeholders have been selected for internationality. The indices are mere placeholders, not related to any basis and, in particular, are non-numerical. All above mentioned placeholders are used unofficially. One of the placeholders in Ubykh, zamsada, may be related to another word meaning "useless". Placeholders for large numbers include "ziljoona" and "biljardi". In Chinese, question words are used as placeholders.