Answer: PHP is a paid service. It is available both within the packages of services (starting with the "Developer" package) and as a separate service ($1.99 per month).

It is forbidden to use such language features as:

• system calls (proc_open, proc_terminate, shell_exec, system etc)
  
• file system low-level functions (dio_fcntl, dio_open, dio_read, dio_seek etc)
  
• shared memory functions
  
• MySQL functions (mysql_stat, mysql_pconnect)
  

You can find examples of what can be done by means of PHP here.

Description of PHP scripts usage.

Answer: At present it is available in 11 modules: blog, board, dir, gb, load, news, photo, publ, stuff, forum, index.

Answer: You can do this in Control Panel -> Settings -> Common settings -> Allow API usage. By default it is disabled.

Answer: You can read about it in the tutorial here.

Answer: Yes, there is. This feature allows to use API only those who know the API key. API will not work for others. You can enable this feature in Control Panel -> Settings -> Common settings -> Use API key. The key is generated automatically.

If you want to change the existing key, disable this feature and then enable again and save the changes.

Answer: To enable PHP you need to purchase "The possibility to use PHP scripts" either as a separate service or within a package of services it is included to. When the PHP service is enabled, an account is created on the separate server. The execution of all PHP scripts is carried out at this server. The access to this account, change and removal of data is carried out via the FTP protocol with a username and password (you specify them when activating PHP). You can see them on the Control Panel main page.

Answer: The list of limitations:

• the maximum amount of the occupied disk space is 200Mb
  
• the maximum amount of files and directories is 10000
  
• the maximum amount of files in directories is 500
  
• the maximum time of script execution is 25 seconds

Answer: See the instructions at the official website: phpexample.ucoz.net