The Manual Form has the following options:
External URL
Sometimes you do not want to customize the form or use automatically generated form, but use external editor/view/page. So you can specify URL for the external page. When you try to open 'Manual Step page' the control is redirected to specified External URL.
Use Automatic Form
The Use Custom Form option is used to create a customized form for the node type “Wait”. The user can write the code in Manual Form text area and click "Generate" -button. The form is generated. The “Preview Generated Form” button is used to preview the generated form as shown below:

Now, click “Preview Generated Form” button. The screen displays the preview of HolidayRequestFrom as shown below:

Use Custom Controller and Form (for development mode only)
The Use Custom Controller and Form option is used to modify or add more additional features to the user customized form, or to create a more complex user customized form. Similar to Use Custom Form create write code in Manual Form text area and click button. To preview the form click “Preview Generated Form” button.
Custom Page and Controller Rules
It displays a pop-up with some code rules and information for the user who wants to specify custom controller/page. The page contains list of variables that are available on the page (variables, transitions, and so on.) To edit or delete process node, click the corresponding Edit or Delete option of nodes, under Operations column.