SHELL

dos assign carriage return to variable

set myLinefeed=^<LF1>
<LF2>
<LF3>

dos assign carriage return to variable

(SET LF=^
%=this line is empty=%
)

dos assign carriage return to variable

if "!LF!" NEQ "!LF:~0,1!" echo Error "Linefeed definition is defect, probably multiple invisble whitespaces at the line end in the definition of LF"

FOR /F "delims=" %%n in ("!LF!") do (
  echo Error "Linefeed definition is defect, probably invisble whitespaces at the line end in the definition of LF"
)

dos assign carriage return to variable

setlocal EnableDelayedExpansion
set LF=^


rem TWO empty lines are required
echo This text!LF!uses two lines

dos assign carriage return to variable

set LF=^


rem TWO empty lines are required
echo This text^%LF%%LF%uses two lines
echo This also^

uses two lines