'translation' of 'bound' and 'column' with regard to hairpins (for non-developers)

[James Lowe]

Hello,

I am currently trying to close out Issue 989. And one of the reg tests says

--
Hairpins extend to the extremes of the bound if there is no adjacent hairpin or 
dynamic-text. If there is, the hairpin extends to the center of the column or 
the bound of the text respectively
--

Can someone tell me what a/the 'bound' is? Also what is a 'column' in this case 
the width of the note head (including the stem)?

the reg test is very simple

\relative c'' { 
  c4 \< c4 \!
  c4 \< c \!\> c\!
  c4 \< c c \!  \fff\> c c\!
  
}

But I'd like to give a nicer explanation for non-developy-people.

James