Inheritance of properties

A virtual variable inherits properties from its operand(s) according to the following rules:

General variable properties are copied from the first operand to the newly created virtual variable.
General variable properties are copied once and once only, i.e. there is no link between variable properties of the operand and virtual variable after the virtual variable has been created.
The settings on the Notes page are not copied.
Operator specific properties are not copied.

Note: A Copy-and-Paste of a virtual variable or virutal variable chain can affect inheritance (see below).

Inheritance of calibration settings

Virtual variables inherit their Transducer and SourceCal (Calibration Source) from the first operand. The first operand's LocalCal (from the operand's Calibration page of the Variable Properties dialog box) is not inherited. However the virtual variable's calibration settings can be set/modified using an ECS file. There are core calibration settings that virtual variables use. Refer to Calibration for virtual variables for more information.

Note:

EV files created with versions earlier than Echoview 5.0 are may not be entirely backwards-compatible. Pre-Echoview 5.0 virtual variable calibration inheritance support is unavailable in Echoview 5. For some data formats, the calibration settings may be different.

In addition, the Transducer for complex (calibration) inheritance chains in pre-Echoview 5 EV files may change to conform with the Echoview 5 rule for the inheritance of properties from the first operand. The Transducer is determined from the first operand (and raw variable) at the start of the virtual chain.

Echoview defines the following calibration inheritance terminology:

Inheritance tree

A tree structure of variable operand relationships, rooted at a virtual variable of interest, which then branches through the variables operand relationships, up to the highest level of raw variables.

Inheritance chain

An inheritance chain is a flow of calibration settings from one variable to another through operand relationships.
For example, take the variable relationship:

A -> B -> C

Where:

A is a raw variable
B is a virtual variable, with A as an operand
C is a virtual variable, with B as an operand

By default virtual variables inherit calibration settings from their operand 1 variable. Using default settings, variable C obtains its Calibration source from variable B, while variable B obtains its Calibration Source from variable A. The Local supplement is not inherited but it can be selected for a virtual variable.

Copy-Paste of virtuals

When pasted a virtual variable or variable chain is unavailable. To make the virtual(s) available, attach an operand or operands. Inheritance of the Calibration source (displayed as SourceCal on the Calibration page) is from the first operand. LocalCal is not inherited.

Borders around a virtual variable

No border means that the virtual variable's Calibration Source is inherited from the first operand. When an ECS file is added to the fileset, the calibration settings of the virtual variable may be affected by the global settings and SourceCal settings in the ECS file..
A red border means that a LocalCal is selected and specific LocalCal settings from an ECS file are used. The LocalCal settings respect prior Fileset and SourceCal settings.

Inheritance of properties

Inheritance of calibration settings

Copy-Paste of virtuals

Borders around a virtual variable

See also