New Object Model
Debugging in PHP
Migrating from PHP 4 to PHP 5.0.x
PHP Manual

## Error Reporting

As of PHP 5 new error reporting constant E_STRICT was introduced with value 2048. It enables run-time PHP suggestions on your code interoperability and forward compatibility, that will help you to keep latest and greatest suggested method of coding. E.g. STRICT message will warn you on using deprecated functions.

> Note: E_ALL does not include E_STRICT so it's not enabled by default

New Object Model
Debugging in PHP
Migrating from PHP 4 to PHP 5.0.x
PHP Manual