When you create a button and set its Control Type to Submit, the Submit tab appears in the Object palette. It displays several options specific to formatting buttons that submit data.
Submits a package in the file format created by Designer ES. Choose this format if the form initiates server-side processing, or to submit the form design, the form data, annotations, and all other relevant information needed for Forms ES to subsequently render the form at run time.
Submits a package containing an embedded PDF file. Choose this format if the form contains a signature field, or if a copy of the form together with its data needs to be saved by Forms ES or submitted to another type of target server. Do not choose this option if the form initiates server-side processing, if Forms ES will be used to render at run time, HTML forms or forms whose layout adjusts, or if the form is a PDF form that will be filled in Adobe Reader without the use of Reader Extensions ES.
Submits an XML data stream, which allows for the hierarchical representation of data and can be parsed by any generic XML parser. Choose this format if the server that communicates with the run-time user application program must receive an XML data steam.
Submits a text stream to the specified Uniform Resource Locator (URL) using the POST method. The text stream can be parsed by an FTP server, a mail server, a web server, or a CGI script that processes HTML forms. To use this method, users must open the form in Adobe Reader 6.0 or later or in a web browser unless the URL specifies the mailto protocol.
Applies a data signature to the submitted data. When a form filler clicks the button, a digital signature is created to cover the submitted data and attachments. Data signatures secure the signed data and guarantee the data integrity during transmission. Data signatures can apply to the form data or to the entire submission, including attachments. You can click the Settings button to define optional security properties for the data signature, such as the signature handler, signing certificates, and certificate issuers.
When selected, includes a PDF version of the form when it is submitted as an attachment; otherwise, a reference to an embedded PDF file is included.
Includes one or more <xdp> elements in the XDP source file. The specified elements must be separated by commas and white space is optional. For example: xci, xslt, sourceset.
See also 

Button properties in the Submit tab