Basic - (example: Hydraulic engineering) searches for the entered expression in an exact match with the entry - i.e. in the order in which the words follow each other.
Logical OR - (example: butterfly valve OR lattice disc) pages containing one, the other, or both of the entered keywords will be included in the results.
Logical AND - (example: ASME AND internal pressure) only pages containing both required words will appear in the results.
Logical NOT - (example: spherical NOT ASME) pages containing the name "spherical" but not containing the word "ASME" will be displayed in the results.
