Barcode verifiers are primarily used by businesses that print and use barcodes. These tests and analyses of operative conditions are performed by PHIUS raters or verifiers. Alternatively, NP can be defined using deterministic Turing machines as verifiers. Alternatively, NEXPTIME can be defined using deterministic Turing machines as verifiers. Potential verifiers must complete thorough training on exactly how to verify every NGBS practice. These certificates can be for domestic or foreign document verifiers. There are many verifiers built on top of the Z3 SMT solver. Verifiers work with project teams to perform the rough and final construction inspections described below. There are also many verifiers built on top of the Alt-Ergo SMT solver. Some proof verifiers, such as Metamath, insist on having a complete derivation as input. There are at least 17 proof verifiers for databases that use the Metamath format. The class of problems with such verifiers for the "no"-answers is called co-NP. The distinction between interactive and in-between verifiers is not a sharp one.