IBM 3270 Operator's Manual page 63

You may encounter situations where the cursor has entered a program-defined
numeric input field (thereby placing the keyboard in Numeric Mode) and you
must enter one or more alphabetic characters. The Alpha ( (). ) shift key is
provided to enable you to enter alphabetic characters into a program-defined
numeric input field. To enter alphabetic characters when the keyboard is in
Numeric Mode, press and hold the Alpha shift key, and then key in the desired
alphabetic character or characters.
After reading this section, turn to "Similar Keys on Typewriter and Data
Entry Keyboards," in this chapter, for descriptions of other keys on the
Data Entry keyboard.
Typamatic (Repeat-Action) Keys
Most of the keys are called typamatic keys. This means that they have the
ability to repeat their characters or their function automatically if held down.
The keys that have this capability are shown in Figure 3-14. The discussion
of each key also mentions the typamatic capability if it applies.
Figure 3-14. Typamatic (Repeat-Action) Keys
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