Hi, Ahmad Ali. F2:3 stands for F2-derived F3. Basically, this population is derived from selfing of the F2 individuals, in order to retain the individual's genetic constitution. This population is useful when we need to validate our QTL results, but F2 will not be available at that time. There are plenty of papers there. Perhaps you need to google 'F2 derived F3', instead of the filial code. Hope this will help.
In addition F2:3 are very suitable for mapping oligogenic traits controlled by recessive genes and QTLs since data can be recorded on multiple plants in each F2:3 family to compensate for sampling error.