13.1 Parameter system
13.2 Data system

13.4 Graphics system

13.6 Database system
13.7 Utilities

ADAM provides subroutine libraries which make various facilities available to application programmers. Each library has a Facility Name which is a mnemonic used to identify it. For example, the Facility Name for one of the libraries in the Starlink Data System is ‘DAT’. The ways in which these Facility Names impact upon the programmer are:

Routine Names

Each routine in a library has a name of the form:

fac_name

where ‘fac’ is the Facility Name, and ‘name’ is the specific routine name. By using this convention, name clashes between different libraries and applications can be avoided. It also becomes possible to identify the ADAM calls in a piece of code.

Error Symbols

The error codes which can be returned via the STATUS argument are given symbolic names using Fortran PARAMETER statements. These names are made available to a program by including a file with logical name ‘fac_ERR’, as in:

INCLUDE ’DAT_ERR’

which includes the symbolic names of error codes returned by the Data System (DAT). This file need only be included by routines which need to identify the precise nature of an error. The symbolic names have the form:

fac__error

where ‘error’ is a mnemonic used to identify the error (note the use of two ‘_’ (underline) characters). The actual values of the error codes originate from the VMS MESSAGE utility, and so form a coherent set with the status returns from VMS libraries. A set of error codes which may be used by writers of non-ADAM facility libraries is provided in the include file USER_ERR.

Parametric Constants

These are symbolic names given to the constants associated with a library. The most commonly needed constants are defined in a file with logical name ‘SAE_PAR’. In the situation where a program requires the parametric constants for other facilities, these must be included by:

INCLUDE ’fac_PAR’

The form of these symbolic constants is identical to that used for error codes, namely:

fac__const

This chapter provides an overview of the most important ADAM libraries. They are grouped into systems. Each system is described in more detail in a subsequent chapter except the database system, which is mainly used in the SCAR applications package, and the utilities, which are described in Starlink User Notes.

### 13.1 Parameter system

This provides the mechanism for controlling the action of ADAM programs:

PAR
[AED/15, APN/6]

This provides high-level access to the parameter system. It makes it easy to input a small number of data values from the terminal and to specify the data objects, devices and so on which the program requires.

### 13.2 Data system

This provides the dominant mechanism by which programs store and manipulate data. The data system as a whole is sometimes referred to colloquially as HDS, and sometimes as NDF. The following facilities are available, listed using a top-down approach:

NDF
[SUN/33, SGP/38]

This stands for Extensible $N$-dimensional Data Format, as described in Chapter 10. It is the standard Starlink format for storing data arrays. As such, it is expected to form the basis of most Starlink ‘image’ processing applications, where ‘images’ include arrays which have more or less than two dimensions.

ARY
[SUN/11, SGP/38]

This is a set of routines for accessing Starlink ARRAY data structures built using HDS. The most likely reason for using these routines directly is to access ARRAY structures stored in NDF extensions.

REF
[SUN/31]

These routines allow you to store references to HDS data objects in special HDS reference objects, and allow locators to reference objects to be obtained. Their main uses are to maintain a catalogue of HDS objects and to avoid duplicating a large dataset.

HDS
[SUN/92]

The Hierarchical Data System is a flexible system for storing and retrieving data, and is of great importance to the whole of the Starlink Project. It is the basic data system in ADAM and is also used in many other software items. It is used very extensively in the implementation of ADAM itself and is also used by application programmers. The routines themselves are mainly concerned with the highest level of the data system, including the container file which is the interface between the data system and the host computer’s file system.

CMP
[SUN/92]

These routines simplify the coding needed to access structure components within HDS.

DAT
[SUN/92, APN/7]

These routines access and manipulate data objects, which may be primitive (e.g. arrays of numbers), or structured (i.e. collections of other objects).

### 13.3 Message and Error systems

These related systems provide the only mechanism by which text should be sent to the command device (user terminal or batch log file). Output will normally go to the command device via a user-interface. The facilities involved are:

MSG
[SUN/104]

Reports non-error information to the user.

ERR
[SUN/104]

Reports error messages to the user and environment.

EMS
[SSN/4]

Constructs and stores error messages, but doesn’t communicate them to the user. It is, therefore, of no interest to the application programmer, but of considerable interest to the programmer who is building new systems software. It is included here for completeness.

### 13.4 Graphics system

This consists of several facilities offering different levels of control, but all (except IDI) are based on the ISO standard Graphics Kernel System (GKS).

NCAR/SNX
[SUN/88, SUN/90, MUD/59]

An extensive suite of high level graphics utilities originating from the National Center for Atmospheric Research in Boulder, Colorado. SNX contains some Starlink-produced extensions to NCAR.

PGPLOT
[SUN/15, MUD/61]

A high level package for plotting x-y plots, functions, histograms, bar charts, contour maps and grey-scale images. The version in use on Starlink uses GKS for its low-level graphics input/output.

NAG graphics
[SUN/29]

The NAG Graphics Library (formerly the Graphical Supplement) was originally seen as a way of plotting data associated with the numerical routines which make up the main NAG library. However, it can be used quite independently of the main library for plotting graphs, functions, and contours, though most people now prefer to use NCAR or PGPLOT.

SGS
[SUN/85]

A ‘simplified’ graphics facility which provides most of the commonly needed basic graphics functions in a convenient form. The primary simplification over GKS is that, while several workstations can be open simultaneously, only one can be active at a given time. It has been designed so that calls to its routines can be freely interspersed with those of GKS. Specialised GKS functions are not reproduced in SGS.

GKS
[SUN/83, MUD/27]

The basic set of ‘implementation’ routines. It is a fairly powerful low-level graphics facility, and is the international 2-dimensional graphics standard.

IDI
[SUN/65]

A standard for displaying astronomical data on an image display. It complements, rather than replaces, GKS, and should be used where intimate control of the image display device is required, and for functions which are outside the scope of GKS.

AGI
[SUN/48]

A database system which stores information about plots on a graphics device. This enables a program to relate to plots produced by other programs.

GNS
[SUN/57]

Almost every Starlink graphics program will need the name of a GKS or IDI device. GNS — the Graphics Name Service — allows the programmer to choose a device from a reasonably ‘friendly’ series of names, which is then translated into the GKS ‘workstation type’. Unless you are opening GKS workstations directly or making specialised enquiries about devices, you are most unlikely to need to call GNS yourself.

### 13.5 Input/output systems

In general, data storage should be handled through the data system. However, there may be a need to handle files directly. This is provided by the following closely related facilities:

FIO
[SUN/143]

Handles sequential, formatted files for the production of reports, e.g. for subsequent listing. The form of carriage control may be specified when the file is created.

RIO
[SUN/143]

Handles unformatted, direct-access files.

There may also be a need to access ‘foreign’ magnetic tapes:

MAG
[APN/1]

Handles tape positioning, and reading or writing data blocks and tape marks. It also includes facilities for keeping track of tape positions so that programs can provide a friendly user interface.

### 13.6 Database system

CHI
[SUN/119]

This is gradually replacing ADC as the preferred method of accessing relational databases, such as the usual astronomical catalogues or large tables of measurements of sets of objects.

Provides access to the relational database files handled by the SCAR programs. It is implemented as part of the SCAR software item.

### 13.7 Utilities

These differ from the libraries mentioned above in that they are not associated with parameters. They are libraries which enable ADAM programs to do various tasks in a consistent way:

CHR SUN/40

Manipulation of character strings, encoding and decoding numeric fields etc.

CNF SGP/5

Interchange of character strings between Fortran and C software modules.

PRIMDAT
[SUN/39]

Arithmetic, mathematical operations, type conversion, and inter-comparison of any of the primitive data types supported by HDS.

PSX
[SUN/121]

An interface to the Posix portable operating system.

SLALIB
[SUN/67]

Routines mainly concerned with astronomical position and time.

TRANSFORM
[SUN/61]

A standard, flexible method for manipulating coordinate transformations, and for transferring information about them between programs.