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OVM scripts follow the Ozterm convention about how script lines are treated. Lines in an OVM script fall into 4 groups which are: command, comment, whitespace, and host command.

@Command Lines

OVM scripts are similar in appearence to the Pascal programming language with some notable exceptions. The first is that every command line must start with the character ‘@’. This is because all non command, or non comment lines are treated as host commands (ie they are to be sent to the currently connected network element). This is to provide backwards compatibility with Ozterm.

@comment("Hello world")      ! display Hello world to the user

Command lines can be continued over the next line by placing the backslash character ‘\’ character at the end of the line but before any trailing comments. This causes the OVM compiler to immediately skip ahead to the start of the next line, and continue processing. Make sure any string literals are closed first.

@comment("Hello there" \     ! line continues on the next line
+". How are you feeling?")   ! this line completes the one above

Note that in the above example the + operator is used to join the two strings back into a single string.

If you don't mind wide lines then there is no need to use the ‘\’ character.

Ozterm supports a special command !$$$$! which indicates the end of a sub-file. This command has been replaced with the command @eosub.

Comment Lines

Any line that starts with ‘!’ (except !$$$$!), or ‘@@’ is considered to be a comment line, and is ignored by the OVM compiler.

! This line is a comment
@@ This line is also a comment

Any Ozterm script files that use the special command !$$$$! (the end of sub file marker) should use @eosub instead. The old syntax is still supported but is not recommended.

Whitespace Lines

Any line that contains only whitespace characters is ignored by the OVM compiler. Whitespace is defined as any combination of spaces and tabs.

! The following line is a whitespace line

! The line above is a whitespace line

Implicit Host Command Lines

Any non blank line that does not start with ‘@’, ‘!’, or ‘@@’ is treated as an implicit host command line (ie it is implicitly expected to be sent to a remote host - eg an AXE exchange). These lines (minus any leading whitespace) are assumed to have meaning to the currently connected network element. Internally the OVM compiler handles these lines through the use of the OVM command @hostcmd.

! The following line is an implicit AXE host command
CACLP;
! The following line is an explicit AXE host command
@hostcmd("CACLP;")

An implicit host command line must not exceed 255 characters in length, cannot be continued using the ‘\’ character, and preferably should not have trailing comments as these will be sent to the network element also. To safely add comments to a host command use the OVM command @hostcmd, or place your comments on a separate line from the host command.

An implicit host command line may also contain variable substitutions. See the section on variable substitutions for more details.

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