NET/MASTER Network Control Language (NCL) Programmer's Guide

Language Elements
NCL Summary
106160 Tandem Computers Incorporated 2–15
DROP explicitly deletes (drops) multiple variables in a single operation. It is used in
relation to variables used by panels and MDO variables. DROP does more than
simply assign a null value to variables; it removes both the variable and its value from
memory.
EVENTTD Verb
NCL processes can read the Event Management Service (EMS) EVENTTD database to
obtain help text records. Users can then use these records to create their own help
database, which can then be searched forward and backward using standard function
keys.
FILE Verbs
NCL processes can work with files or file pairs. Any file that NCL can process is
called a user database (UDB); any file pair that NCL can process is called a UDB pair.
A single UDB can be an entry-sequenced or key-sequenced file, an edit file, or a
Guardian process. A UDB pair is two key-sequenced files that are treated as a single
unit in all file processing. (Section 12, “Working With Files,” discusses the
characteristics of the key-sequenced files in UDB pairs.) When working with UDB
pairs, one UDBCTL command or FILE verb refers to both files in the pair.
There are many FILE verbs that you can use to work with UDBs and UDB pairs (FILE
OPEN, FILE CLOSE, and so on). FILE verbs are available for opening and closing a
UDB or UDB pair; adding, updating, deleting, and retrieving records from a UDB or
UDB pair; setting current UDB characteristics; and communicating with Guardian
processes.
CMDLINE, WRITE, PAUSE, DELAY, OCS, and QEXIT Verbs
NCL processes can interact with users and terminals. The CMDLINE, WRITE,
PAUSE, DELAY, OCS, and QEXIT verbs are used to do this.
CMDLINE displays text on the OCS command input line. WRITE sends a message to
a specified destination, typically to the OCS message display area or to another NCL
process. (SAY is equivalent to WRITE TERM=YES LOG=NO.)
PAUSE suspends execution of an NCL process until it is explicitly requested to
continue or terminate. DELAY suspends NCL process execution for a specified
number of seconds.
Another verb that affects interaction with users and terminals is the OCS verb. This
verb calls OCS from an NCL process. When you type X from the OCS command input
line to exit from OCS, control returns to the NCL process.
The QEXIT verb is used to quickly terminate the execution of an NCL process.
PANEL and PANELEND Verbs
Panels are a more sophisticated way of communicating with users and terminals than
by using CMDLINE, WRITE, PAUSE, and DELAY. Panels are formatted screen