When customizing a macro definition, the HTML specifications for white space must be taken into consideration. For 3270 terminals, blanks (EBCDIC X'40') and nulls (EBCDIC X'00') can be used to format screen data positions. When such a data stream is converted into HTML, the client interpretation of this generates different output to that found on a 3270 terminal.
A string of blanks is ignored by a client if it immediately follows a start tag, and any subsequent sequence of contiguous blanks is interpreted as one blank. To force the rendering of all blanks, you can use the <pre> and </pre> tags.
The handling of null characters is unspecified, and clients handle them inconsistently. They may or may not be displayed.