# Language Reference

Appendix |

This Appendix contains information about the additional aspects of the PxPlus language, such as file options, labels, launch command syntax, operators, and control codes. It also includes supplementary information regarding pre-set system limits, error messages and reserved words.

The following links provide additional information:

Help Topic | Description
COM Ports and Serial Devices | Methods for opening a COM port for direct serial communication and access to serial devices.
Input/Output and Control Options | Various options that can be included in a directive or system function to fine tune code and redirect processing.
Data Format Masks | Character string masks used to define data (input/output) in PxPlus.
Displaying Bitmaps/Icons | Associating images (bitmaps or icons) for use within a PxPlus program.
Negative CTL Definitions | Actions that are assigned to negative CTL values, and have special significance to PxPlus.
Operators | All operators that can be used in PxPlus, including: property, assignment, auto-increment/decrement, LIKE, and the Apostrophe Operator.
Apostrophe Operator | Information on the use of the Apostrophe Operator.
Labels/Logical Statement References | Built-in statement labels that can be used instead of line number references in applications.
Reserved Words | Words that are reserved for internal use by PxPlus.
Setting Up Web Server as a Windows Service | Methods for installing PxPlus Web Server as a Windows Service.
System Limits | Preset system limits of PxPlus.
Error Codes and Messages | The numeric system variable ERR, error codes, and the messages associated with errors detected by PxPlus.
Returning Error Codes and Messages | A simple technique that can be used to return an error condition and a message to a calling application.
Customizing Radio Buttons and Check Boxes | Information on customizing the default Radio Button and Check Box display.
NOMADS Library Variables | Lists the NOMADS library variables.