Performs a short term forecast (STF) to hit the target F in year ay+1. The resulting catch in year ay+1 is the TAC, i.e. the TAC that will result in Fbar = Ftarget. The STF uses geometric mean recruitment. Fbar in the intermediate years (i.e. years between last data year and ay+1) are set as the mean of the last nsqy years. The control argument is a list of parameters: nsqy - number of years to average over to get Fbar for STF delta_tac_min - constraint on the TAC delta_tac_max - constraint on the TAC

```
tac.is(
stk,
ctrl,
args,
dtaclow = NA,
dtacupp = NA,
recyrs = 10,
fmin = 0,
initac = catch(stk[, ac(iy - 1)]),
tracking
)
```

- stk
The perceived FLStock.

- imp_control
A list with the elements: nsqy, delta_tac_min, delta_tac_max

- ay
The year for which the target F is set, based on the SSB in year (ay - control$ssb_lag).

- EFF0
The tracking array

- EFF
Not used by this function but may be used by the other implementation functions

```
data(sol274)
#> Warning: namespace ‘DBI’ is not available and has been replaced
#> by .GlobalEnv when processing object ‘om’
```