PROG_FULL_THRESH is a user-defined threshold that defines when a specified number of words have been written to the FIFO, and can be used to determine the amount of available space remaining in the FIFO. When the number of words is more than or equal to PROG_FULL_THRESH, the PROGFULL signal is asserted. If PROGFULL = 0, the number of words in the FIFO is less than PROG_FULL_THRESH. Similar to the PROGEMPTY assertion, the PROGFULL flag conservatively represents the number of words in the FIFO relative to the PROG_FULL_THRESH setting. Therefore, PROGFULL considers all write operations but might not immediately update due to read operations synchronization latency. Thus, it can sometimes present the FIFO as being more full than it actually is.