i don't know php myself but this might help:

 http://perl.about.com/library/phpCR/bl_escape_sequences.htm

Finally I can voice myself in this forum. hehe.

/n means new line character it is different with <br>, because <br> is an HTML tag while /n is a computer character.

in php if you
echo "Lunar <br> Pages";
Your browser will display it as

Lunar
Pages

BUT for
echo "Lunar\n Pages";
your browser display

Lunar Pages

!!! becuase HTML ignore white spaces characters(space, new line characters, tabs ...). To see what the \n actually did, you can select view -> source in IE to see the source code, for the 1st example using <br> you get source code

Lunar <br> Pages

for the 2nd example using \n you will see

Lunar
Pages

Get the point? In HTML even 1,000,000 white space characters are treaten as one single space. So \n are use to format your source code nicely so that you can debug/check your PHP output easily. (Else all your code is joint in a single line!)

So as \t. \t it is tab character. You will see the TAB in your source code but it will not be display the TAB.

for \r is return character and \v is vertical chacacter, explanation for this 2 will be lenghtly (Is is back to the DOS world where \r means return to the left side of the screen, \v means move to next line but below). Ignore them as they are very confusing. You don't need to use them in PHP scriping.