BEFORE THE FIELD AGENT CAN SUBMIT AN ENCOUNTERED SUBSTANCE FOR ANALYSIS, SUFFICIENT CAUSE MUST EXIST TO BELIEVE THAT THE SUBSTANCE MIGHT BE LEGALLY CONTROLLED. SUCH INDICATORS AS FORM, QUANTITY, ENVIRONMENT, SMELL, AND TASTE ARE COVERED. FIELD TESTS INVOLVING COLOR-PRODUCING CHEMICAL REACTIIONS MAY ALSO BE USED TO AID THE AGENT IN ELIMINATING POSSIBILITIES. IN ADDITION, THE PERSON FROM WHOM THE SUBSTANCE WAS OBTAINED MAY BE A SOURCE OF INFORMATION. ONCE A DETERMINATION HAS BEEN MADE TO SUBMIT A MATERIAL FOR ANALYSIS, STRICT GUIDELINES REGARDING PACKAGING AND IDENTIFICATION FOR TRANSFER TO THE LABORATORY MUST BE FOLLOWED. INSRUCTIONS ARE ALSO GIVEN FOR THE CORRECT HANDLING OF VEGETABLE MATTER (SUCH AS MARIJUANA, CACTI, AND MUSHROOMS) AND PARAPHERNALIA (SUCH AS SYRINGES AND SMOKING DEVICES). THE LAST STEP IN THE PROCESS IS COMMUNICATION WITH THE LABORATORY; THE AGENT'S EVIDENCE/PROPERTY CUSTODY DOCUMENT AND REQUEST FOR LABORATORY EXAMINATION CAN PROVIDE THE ANALYST WITH CLUES AS TO THE IDENTITY OF THE SUBSTANCE. ACCURACY AND CAREFUL HANDLING THROUGHOUT THE SEQUENCE ARE STRESSED.