How to search for HEX 00 in unicode systems?

I am aware that cl_abap_char_utilities provides many non-printable characters (such as horizontal_tab). However, I am looking for a way to represent HEX 00 in a char variable so I can search for it in text strings.

If I uncheck the "unicode check" checkbox, I can easily assign HEX 00 to a char variable. However, I don't like to disable unicode check.

An explanation of how SAP has implemented cl_abap_char_utilities=>horizontal_tab will also help. Looking at the class builder, it is defined as %_HORIZONTAL_TAB in "Initial value" column. What does that mean?

Thank you very much for your time.