The literals of the rule expressions may have attributes. Literal attribute are mostly for back-end tool-specific use.
Specifies that a transistor has low-Vt type, mainly for netlist generation and LVS checking.
Specifies that a transistor has standard-Vt type, mainly for netlist generation and LVS checking. This is also the default type, when Vt is left unspecified.
Specifies that a transistor has high-Vt type, mainly for netlist generation and LVS checking.
Ideas:
Instance-specific attributes?
Procedural layout?
Automatic sizing