Thanks a lot for the clarification Wolfgang.
 
I guess I was still playing with this kind of major flawed thinking coming from WYSIWYG wordprocessors where isn't concerned thinking about these technical aspects (what's underneath), instead type/edit as characters appear on screen in real time, then when switching to typesetting systems extrapolate and expect things to work in the same way. 
 
I'll digg into the manuals' corresponding chapters to get more familiar with these technicalities and let them sink in.
 
Best,
Alan
On Sun, Jan 4, 2009 at 8:54 PM, Wolfgang Schuster <schuster.wolfgang@googlemail.com> wrote:

Am 04.01.2009 um 20:30 schrieb Alan STONE:


On Sun, Jan 4, 2009 at 6:35 PM, Wolfgang Schuster <schuster.wolfgang@googlemail.com> wrote:

Am 04.01.2009 um 18:26 schrieb Alan STONE:

\starttext

\setbox\scratchbox\hbox{\switchtobodyfont[38pt]Text In A Frame}

\the\htdp\scratchbox

\stoptext

From this example I conclude TeX does not do what you tell it to do.

I must be missing something... ?

What do you not understand in my example?

From what I understand of it: asked 38pt, output 26.18pt

The 26.18pt are only the height of the sample text, not each character
has the height of the font size which includes the height and depth.

You can see here the output is correct and only characters with large
height and depth match the given fontsize.

\starttext
\setbox\scratchbox\hbox{\switchtobodyfont[38pt](}
\the\htdp\scratchbox % 37.45pt
\stoptext

I show you in another example why you value for the interlinespace
is to small for characters with depth.

\starttext

\vbox
 {\switchtobodyfont[38pt]
  \setupinterlinespace[line=30pt]
  \lineskiplimit-\maxdimen
  Big text\crlf written in\crlf three rows\par}

\stoptext


Wolfgang