The first thing you probably will notice is that PHP's start and end tags have changed. The old <? > form has been replaced by three new possible forms:
Example#1 Migration: old start/end tags
<? echo "This is PHP/FI 2.0 code.\n"; >
Example#2 Migration: first new start/end tags
<? echo "This is PHP 3.0 code!\n"; ?>
Example#3 Migration: second new start/end tags
<?php echo "This is PHP 3.0 code!\n"; ?>
Example#4 Migration: third new start/end tags
<script language="php">
echo "This is PHP 3.0 code!\n";
</script>