Language Reference Guide > Language Reference Guide > System Classes > How You Can Use This Chapter > Attribute Abbreviations
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Attribute Abbreviations
The following table describes the abbreviations used in this chapter to indicate how you can access each attribute:
4GL Access
Description
RW
Read and write this attribute
R
Read-only attribute
W
Write-only attribute
W1
Write this attribute once
RW1
Read this attribute and write it once
Note:  Code that changes the values of attributes defined as read-only (R), write-only (W), or read-write-once (RW1) by explicit assignment is not supported. Such code typically will fail, but in future releases of OpenROAD, such code likely will encounter a compile-time or runtime error. Ensure that your code does not set or reset these attributes.
For many attributes, you must assign values using special system constants, such as LW_VERYTHIN (for line width attributes) or FT_TABTO (for tabs). See System Constants and Keywords for more information about these constants. For attributes that can have a value of true or false, use the Boolean system constants TRUE and FALSE.
For more information about attribute prefixes (see Property Setting Prefixes) (for example, FT_, LW), see the Workbench User Guide.
Last modified date: 12/20/2023