NOS iap question

[stlcards]

When looking at the comm brief strip on NOS charts, does anybody know why some of those boxes are bold and some are not? Here is an example on a bis ils the tower box is bold but nothing else. http://myairplane.com/databases/approach/pdfs/00051I13.PDF

Thanks

 

[DC8 Flyer]

Near as I can tell, is it is always the tower or the CTAF freq. that is in a bolded box, I think just to making finding the freq easier, but not sure on that.

 

[transampilot]

I had never noticed that, so, I looked up a couple airports and the one with atleast a part time tower or better have the tower comm box bolded. Uncontrolled airports with CTAFs are not bolded. I looked in the aeronautical chart user's guide and this is the quote---
"The bottom row contains air to ground communication
facilities and frequencies in the order in which they are
used during an approach with the tower frequency box
bolded."
Why they did this? Probably as DC8 flyer pointed out, it's too call your attention to it. IMO
http://naco.faa.gov/content/naco/online/pdf_files/7th_IAP_Intro.pdf​

 

[Amish RakeFight]

I'd have to agree too. Bold so it stands out and is easier to find on the chart.