If Use regex is selected, the entered text will be interpreted as a Regular Expression. Standard PCRE syntax is used. Some examples:

• match lunch followed by Martha with anything in between: lunch.*Martha
• match Bill or Will: [BW]ill
• match meeting or conference: meeting|conference
• match The, but only at the start of the string: ^The
• match case-insentitively, e.g., ATTN, or attn, or aTTn, etc.: (?i)attn