Environment > Getting Started > Using IDL Help

# Using IDL Help

IDL provides both installed, browser-based program documentation, known as the IDL Help System, as well as web-based documentation available via the Exelis VIS website (the Documentation Center).

This topic covers how to open the installed IDL Help System from both the command line and in the Workbench, a brief tour of what is included in the help, tips for searching, and how to access IDL help on the internet.

## Opening the IDL Help System

There are different ways to start the IDL Help System :

### From within the IDL interface:

- Type the "?" command at the IDL prompt to bring up the main help system page.
- Select Help > Help Contents from the IDL Workbench menu.

Additionally, using the "?" followed by a function name opens the help system inside the topic for that function. For example, typing the following at the IDL prompt:

?ARROW

brings up IDL Help open to the ARROW topic.

### On Windows

If using the defaults during installation, the IDL Help System can be started from the Start> Programs > IDL x.x > Help > IDL Help menu.

### On UNIX/Linux/MAC:

The IDL Help System can be started using the `idlhelp` command in a terminal.

## What Does IDL Help Include?

The IDL Help System includes:

- Extensive reference on IDL routines, with explanations of syntax, arguments, keywords and code examples.
- A large collection of tutorials that walk you through the use of IDL graphics, functions, and routines.
- Discussion on the IDL Development Environment, better known as the Workbench.
- IDL Release Notes, IDL system requirements and the Advanced Topics in Licensing in PDF format are available on the installation DVD in the /<media>/info/ folder. IDL Release Notes and the Advanced Topics in Licensing documents are also available as links when you download IDL or the IDL License Server from our website.

## Tips for Searching in IDL Help System

The IDL Help System installed on your computer includes a feature for search on text found in the documentation. The search box is located in the upper right corner of your Help screen.

Here are a few tips for using the search functionality:

- Single-word searches work best. For example, type "syntax" rather than "IDL syntax" to bring up a list of pages containing the word "syntax".
- If searching for special character ("+", for example), surround the special character in double-quotes in the search box: "+".
- Searching is case-insensitive.

## Documentation Center

For IDL 8.2 or later, the Help System and PDF files can also be found on the Documentation Center on the Exelis VIS website at:

http://www.exelisvis.com/docs/home.html

http://www.exelisvis.com/docs/PDF_Guides.html