This error occurs when the attribute name(%s) is empty in the definition.
Add the required attribute name.
Example
[System: Variables]
Variable : MyVar
[Variable: MyVar]
Type : Logical
: Yes
In the variable definition MyVar, the attribute name is empty for the value Yes. Hence the message error T0012: Could not understand the attribute ':Yes'. Attribute name is empty. appears.
To correct the code, the attribute Default is specified for the orphaned attribute value Yes .
[System: Variables]
Variable : MyVar
[Variable: MyVar]
Type : Logical
Default : Yes