Agilent Technologies ESA Series User's/Programmer's Reference page 173

Two. Field One is viewed as having 263 lines (or 313
lines) and Field Two is viewed as having 262 lines
(or 312 lines).
For the 525 line NTSC video standard, we refer to TV
lines as follows (these are the Field Modes):
Entire Frame, lines 1 to 525
Field One, lines 1 to 263
Field Two, lines 1 to 262 (note that this really refers
to "actual" lines 264 to 525)
For the 625 line PAL and SECAM video standards, we
refer to TV lines as follows:
Entire Frame, lines 1 to 625
Field One, lines 1 to 313
Field Two, lines 314 to 625
As the Field is changed, the appropriate value for Line
is chosen to keep triggering on the same line as before,
or if this is not possible, the corresponding line in the
new Field. For example, suppose line 264 is selected
while in the NTSC-M standard and the Entire Frame
mode. This is the first line in Field Two. If Field Two is
then selected, the Line number changes to Line 1, the
same actual line in the TV signal. If Field One is then
selected, the line number stays at 1, but now we are
triggering in the first line in Field One. The only
exception to this is if we are on the last line of Field One
and change to Field Two. In this case, we go to the last
line in Field Two.
Key Access:
Entire Frame
Field One
Chapter 2
,
Trig More, TV Trig Setup
Causes the selected line number to be
viewed as an offset into the entire
frame starting with line 1, the first line
in Field One.
Key Access: ,
Trig More
Field
Causes the selected line number to be
viewed as an offset into the first field
starting with Line 1, the first line in
Field One.
Key Access: ,
Trig More, TV Trig Setup
Field
Front-Panel Key Reference
Trig
, ,
TV Trig Setup
,
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