Sekonic SR-2300 Manual page 59

Direct under type
If paper has pre-printed timing marks, the scanning area (reading area) of targeted
mark frames will be determined by such timing marks.
Direct under type refers to a method of reading a zone that is the same as the timing
mark width.
Other methods include timing control type, mark to mark type, and FACOM type.
Timing mark
Transmission interface
The hardware connecting a computer and the OMR, in other words the mediating
connection. The SR-2300 uses USB or RS-232C interfaces.
Dropout color
Refers to colors pre-printed or written on documents that people can see but that
don't appear when read with an image scanner or other devices.
There are "warm colors" and "cold colors" by appearance. Warm colors called orange
end, red end, etc. are used as OCR dropout colors, and you need to switch filters in
this device for bluish dropout color sheets such as the standard forms used by the
Japan Chain Stores Association. Bluish colored lines drop out when they are scanned
with copy machines and other devices even if they don't use dropout color ink. OCR
paper for fax machines uses "cold color (blue-green)" dropout colors, but there are
only a few colors that can be used with most fax machines, because they are different
from OCR units.
(1) Dropout color print darkness is controlled by the PCS value. There are two
ways to measure PCS, black backing and white backing, and you should
pay attention because they differ depending on the model. See the "PCS"
page.
(2) OCR sheets are generally used for printing character boxes using dropout
color inks and printing letters in clear areas. See the print specification page.
(3) Recently, some models have become available that are capable of reading
black character boxes, but dropout color printing sheets are often superior in
both recognition performance and processing speed.
(4) Dropout colors are chosen by spectral characteristics and PCS values that
are determined by scanner sensor, light source, and filter.
See the spectral characteristic page (spectral characteristic of printing ink)
Mark frame
OMR glossary
Reading area
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