Routines (alphabetical) > Routines: H > HDF Routines > HDF_AN_START

# HDF_AN_START

This function initializes the HDF AN interface for the specified file. A call to HDF_AN_START is required before any HDF AN functions can be invoked. HDF_AN_START is used with the HDF_AN_END function to define the extent of an HDF AN session. A call to HDF_AN_END is required for each call to HDF_AN_START.

## Syntax

Result = HDF_AN_START(file_id)

## Return Value

Returns the HDF AN interface identifier (Annotation_id) if successful or FAIL (-1) otherwise.

## Arguments

### File_id

File identifier returned by HDF_OPEN. Note that each call to HDF_OPEN must be terminated with a call to HDF_CLOSE.

## Keywords

None

## Version History

5.2 | Introduced