| | | | Like CSS operators, the regular expression (RE) syntax specifiers are processed in a specific order. The order of precedence for basic regular expressions (BREs) and extended regular expressions (EREs) are described below, from highest to lowest. The specifiers in each category are also listed in order of precedence. The order of precedence for regular expressions is: Collation-related bracket symbols | [==] [::] [..] | Special characters | \spec_char | Bracket expressions | [ | Subexpressions and backreferences | \( \) \n | Repetition | * \{m\} \{m,\} \{m,n\} | Concatenation | | Anchoring | ^ $ | The order of precedence for Extended Regular Expressions is: Collation-related bracket symbols | [==] [::] [..] | Special characters | \spec_char | Bracket expressions | [ | Grouping | ( ) | Repetition | * + ? {m} {m,} {m,n} | Concatenation | | Anchoring | ^ $ | Alternation | | | |