RegexExpression.ZeroOrMany is a loop that parses zero or more RegexExpression elements. Unlike its counterpart from RuleExpression it is "nonresistant". Given the following grammar:
with a string like:
тthe 'a'* loop will parse the first two letters a, leaving the last a to the following rule (literal), whereas the RuleExpression.ZeroOrMany loop will "consume" all three of them, which will guarantee the following rule to fail. The difference in the behavior is explained by the fact that the RuleExpression parsing uses recursive descendant method, whereas the RegexExpression parsing employs the conversion to DFA.