because one backslah is not important in csh
needed X2

both of '\' and 'n' escape its special means
then
\\ --> \
\\ --> n

5 backslah also same state ( last of \ like newline char in shells and doesnt anything in command in below)

Code:

# echo RECORDDELIMITER \
? \\\\n
RECORDDELIMITER \n

Code:

# echo RECORDDELIMITER \\\\\n
RECORDDELIMITER \n

actually

Code:

\n

is special character it has a mean

Code:

# eval echo RECORDDELIMITER '\A'
RECORDDELIMITER A

eval(actually csh) trying process but \A has no special mean on csh
it will be process only echo and one of backslahs isnt here

Code:

# eval echo RECORDDELIMITER '\\A'
RECORDDELIMITER \A

And '\' and 'n' is a char in csh

Code:

# eval echo RECORDDELIMITER '\\ \n'
RECORDDELIMITER \ n

Regards
ygemici