Assay Codes Codes used for assays, such as system and user censors. Reasons for not running an assay censor codes This section lists the censor codes that can be used on an assigned test when the test will not be performed. Immunology assay codes Codes for immunology assays. Virology assay codes Codes for virology assays. Pharmacology assay codes Codes for pharmacology assays. P24 system censor codes This section lists the P24 assay system censor codes available in LDMS. GeneXpert MTB-RIF system censor codes These are the system censors for the GeneXpert MTB-RIF assay.