# How to interpret factor coefficients regarding unobserved values?

I am presented with a linear regression result that yields the following coefficients:

Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept)                            0.627502   0.010139  27.782  < 2e-16 ***
A_num                                  0.047047   0.004919   9.703  3.7e-16 ***
Bhigh                                 -0.015863   0.004608  -3.510 0.000668 ***
Cin                                   -0.018517   0.003504  -2.801 0.006095 **


Where B has levels of (high, low) and C has levels of (in,out). This would, in my understanding provide four different intercepts one for each of the following

• high, in
• high, out
• low, in
• low, out

However, I do not happen to have any observations regarding one of them, say (high, in). I know that such observations must exist, but the sample does not include any such observation.

Would it still be valide to extend the interpretation to the unobserved scenario?