F1F2

F1F2 is a shorthand that appears in various disciplines and contexts. It does not refer to a single, universal concept, but rather to the pair of items designated as F1 and F2 in a given field, or to the combined usage of the two in casual reference.

In genetics and breeding, F1 and F2 denote first and second filial generations. The F1 generation results from crossing two true-breeding (P) lines. The F2 generation arises from selfing or crossing F1 individuals, revealing segregation of traits according to Mendelian principles. F2 often shows greater phenotypic variation and is used to study inheritance patterns, dominant and recessive traits, and linkage.

In computing and user interfaces, F1 and F2 are function keys on a standard keyboard. They have different default actions depending on the software: F1 typically opens help, while F2 commonly initiates a rename or editing command in file managers and many applications.

In data analysis and machine learning, F1-score and F2-score are harmonic means used to balance precision and recall; they are usually reported separately, not as a single metric labeled “F1F2.” The concept of combining them informally may occur in discussions about model evaluation, but it is not a standard metric.

Because meanings vary by context, F1F2 is best interpreted by its surrounding discipline.