Campbell Scientific CR9000X Measurement and Control System - Manual (Page 341)

Section 9. Program Control Instructions
Syntax 2 Description
Syntax 2 has these parts:
Part Description
If
Keyword that begins the block If...Then decision
control structure.
condition1 Same as condition used in the single-line form shown
above.
Then Keyword used to identify the actions to be taken if a
condition is satisfied.
statementblock-1 One or more CRBasic statements executed if condition1
is true.
ElseIf Keyword indicating that alternative conditions must be
evaluated if condition1 is not satisfied.
condition2 Same as condition used in the single-line form shown
above.
statementblock-2 One or more CRBasic statements executed if condition2
is true.
Else Keyword used to identify the actions taken if none of
the previous conditions are satisfied.
statementblock-n One or more CRBasic statements executed if condition1
and condition2 are both false.
End If Keyword that ends the block form of the If...Then.
In executing a block If, CRBasic tests condition1, the first numeric expression.
If the expression is true, the statements following Then are executed.
If the first expression is false, CRBasic begins evaluating each ElseIf condition
in turn. When CRBasic finds a true condition, the statements immediately
following the associated Then are executed. If none of the ElseIf conditions is
true, the statements following the Else are executed. After executing the
statements following Then or Else, the program continues with the statement
following End If.
The Else and ElseIf clauses are both optional. You can have as many ElseIf
clauses as you like in a block If, but none can appear after an Else clause. Any
of the statement blocks can contain nested block If statements.
CRBasic looks at what appears after the Then keyword to determine whether
or not an If statement is a block If. If anything other than a comment appears
after Then, the statement is treated as a single-line If statement.
A block If statement must be the first statement on a line. The Else, ElseIf,
and End If parts of the statement can have nothing but spaces in front of them.
The block If must end with an End If statement.
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