"I" is seen as a timezone (Like L or Z could be). There is thus nothing wrong with that specific string. However, in the first one the parser sees many different timezone strings, parsing with date_parse() shows:

derick@kossu:~/dev/php/php-5.3dev$ sapi/cli/php 
<?php
var_dump(date_parse("i like to eat slices at work"));
?>
array(16) {
  ["year"]=>
  bool(false)
  ["month"]=>
  bool(false)
  ["day"]=>
  bool(false)
  ["hour"]=>
  bool(false)
  ["minute"]=>
  bool(false)
  ["second"]=>
  bool(false)
  ["fraction"]=>
  bool(false)
  ["warning_count"]=>
  int(6)
  ["warnings"]=>
  array(6) {
    [2]=>
    string(29) "Double timezone specification"
    [7]=>
    string(29) "Double timezone specification"
    [10]=>
    string(29) "Double timezone specification"
    [14]=>
    string(29) "Double timezone specification"
    [21]=>
    string(29) "Double timezone specification"
    [24]=>
    string(29) "Double timezone specification"
  }
  ["error_count"]=>
  int(0)
  ["errors"]=>
  array(0) {
  }
  ["is_localtime"]=>
  bool(true)
  ["zone_type"]=>
  int(2)
  ["zone"]=>
  int(-540)
  ["is_dst"]=>
  bool(false)
  ["tz_abbr"]=>
  string(1) "I"
}

I don't know whether I can make a double timezone string an error, as it's common to use things like "GMT+04:00" which would trigger the same error then - while being a valid string. I think the most I can do if when it sees *more* than two timezones it turns it into errors.

Thanks for the detailed and useful explanation.  Checking for more than 
two occurrences of timezone specification and returning false is such a 
scenario would be the way to go I agree.

Thanks very much,

Chris.

This is in CVS now (or was for some weeks).