The available documentation consists of the NCHS series report titled "Plan and Operation of the Second National Health and Nutrition Examination Survey 1976-80" and the documentation for each data file. The Plan and Operation report contains general information about the survey objectives, statistical sample design, and an overview of the exam components. The report also contains an appendix with all data collection forms, including all questionnaire forms used for data collection as well as forms used for exam components such as the body measurements and the Physician's exam. The report is available as an Adobe Acrobat PDF file. Use the search feature to speed up your search for variables relevant to your analysis. However, read the documentation for each "hit" in your search results carefully, as not every result returned will be relevant to your analysis.
For example, assume you are preparing for an analysis using blood pressure variables, and search the Plan and Operation report file for "blood pressure." Some blood pressure questions were asked in relation to kidney disease in the Medical History Questionnaire. However, the main collection of standardized blood pressure measurements was conducted on all eligible participants aged 6 years and older in the Physician's Exam section of the survey. These are the blood pressure examination variables you would want to use in your analysis.
In addition in the Physician's Exam data collection form you will find spaces on the first page of the form where blood pressure was measured at the start of the exam, and on the last page of the form spaces where a second sitting blood pressure was measured at the end of the exam. You may want to include all of these variables in your analysis.
You must read the documentation to know this information and identify the correct variables for your analysis.