I think the program itself searches for hex bytes and replaces with hex bytes. The ANSI/OEM choice just determines what symbols to display on the screen for the hex bytes.
I tried switching to OEM via TOOLS -> CUSTOMIZE -> EDITING (left side pane) -> Default Editing Fonts, select OEM. I currently have OEM set to “Terminal” font, and ANSI set to “Courier New Special” font (same as “Courier New” except there’s a slash through the zero. It’s available in the User Created Macros forum).
I notice the text in the windows changes when I switch to OEM mode. I notice the FIND and FIND/REPLACE dialog windows still display ANSI characters, but FIND still finds the correct hex bytes even though they appear different in the window.
e.g. if the text file has a hex 02 byte in it; in OEM mode it displays a black happy face character; do a FIND, cut and paste in that black happy face character, and it shows up in the FIND field as an upside down T character, but click ‘Search’ and it finds the black happy face character as desired.
e.g.2: if the text file has a hex FB character, in OEM mode it displays in the window as a square root sign; do a FIND, cut and paste that square root character into the FIND field, and it shows up as a u with circumflex, but click ‘Search’ and it finds the square root sign character as desired.
I don’t know if it’s possible to make Multi-Edit display OEM characters in search fields.