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3. Character and numeric subject-level population flag names end in FL and FN, respectively. Similarly, parameter-level population flag names end in PFL and PFN, and record-level population flag names end in RFL and RFN. Please also refer to ADD LINK Item 8 in Section 3.1.1, General Variable Conventions.

4. For subject-level character population flag variables: N = no (not included in the population), Y = yes (included). Null values are not allowed.

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8. In addition to the population flag variables defined in ADD LINK Section 3, Standard ADaM Variables, other Population Indicator Variables for ADSL Datasets other population flag variables may be added to ADaM datasets as needed, and must comply with these conventions.

9. For character flags with variable names that end in FL and that are not population flags, a scheme of Y/N/null, or Y/null may be specified. As indicated in ADD LINK Tables 3.3.4.3.1 and 3.3.8.1 Analysis Parameter Criteria Variables for BDS Datasets and Indicator Variables for BDS Datasets, some common character flags use the scheme Y/null. The choice of Y/N/null vs Y/null is dependent on analysis needs. Y/N/null should be used when N and null values need to be analyzed differently. Y/null can be used when the need is to analyze just the Y values. Corresponding 1/0/null and 1/null schemes apply to numeric flags with variable names that end in FN and which are not population indicators.

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