[PHP] Naming Convention

╔═══════════════════════╦═════════════╦════════════╦══════════════╦════════════╦════════════╗
║      PHP Project      ║   Classes   ║  Methods   ║  Properties  ║ Functions  ║ Variables  ║
╠═══════════════════════╬═════════════╬════════════╬══════════════╬════════════╬════════════╣
║ Akelos Framework      ║ PascalCase  ║ camelCase  ║ camelCase    ║ lower_case ║ lower_case ║
║ CakePHP Framework     ║ PascalCase  ║ camelCase  ║ camelCase    ║ camelCase  ║ camelCase  ║
║ CodeIgniter Framework ║ Proper_Case ║ lower_case ║ lower_case   ║ lower_case ║ lower_case ║
║ Concrete5 CMS         ║ PascalCase  ║ camelCase  ║ camelCase    ║ lower_case ║ lower_case ║
║ Doctrine ORM          ║ PascalCase  ║ camelCase  ║ camelCase    ║ camelCase  ║ camelCase  ║
║ Drupal CMS            ║ PascalCase  ║ camelCase  ║ camelCase    ║ lower_case ║ lower_case ║
║ Joomla CMS            ║ PascalCase  ║ camelCase  ║ camelCase    ║ camelCase  ║ camelCase  ║
║ modx CMS              ║ PascalCase  ║ camelCase  ║ camelCase    ║ camelCase  ║ lower_case ║
║ Pear Framework        ║ PascalCase  ║ camelCase  ║ camelCase    ║            ║            ║
║ Prado Framework       ║ PascalCase  ║ camelCase  ║ Pascal/camel ║            ║ lower_case ║
║ SimplePie RSS         ║ PascalCase  ║ lower_case ║ lower_case   ║ lower_case ║ lower_case ║
║ Symfony Framework     ║ PascalCase  ║ camelCase  ║ camelCase    ║ camelCase  ║ camelCase  ║
║ WordPress CMS         ║             ║            ║              ║ lower_case ║ lower_case ║
║ Zend Framework        ║ PascalCase  ║ camelCase  ║ camelCase    ║ camelCase  ║ camelCase  ║
╚═══════════════════════╩═════════════╩════════════╩══════════════╩════════════╩════════════╝

References

1. https://softwareengineering.stackexchange.com/questions/149303/naming-classes-methods-functions-and-variables