The aim of this paper is to study on establishment of range and classification of optionality. Preexistence concept of optionality in rule-based theory has its limit, which is that the study on optionality is still in list of optional rules. For this reason, diverse aspects of phonological phenomena in current Korean cannot be explained by existing concept of optionality in rule-based theory. So in this paper, I extended of optionality range in order to including diversity of phonological aspects in contemporary Korean. And then, I classified optionality into two types under two standards each other. Two standards follow as; rule-concerned ways, phonological environments. I classified optionality from rule application or not and optionality from selective application of rules under first standard, outright optionality to phonological environment and not under second standard.