No, the 17 cm spacing would be the original STC (for cardioid capsules; it is sometimes called the "STC 4" now that there are other versions). 17 cm is also the spacing for the MSTC twin microphone, which was developed some years later, because that is the correct spacing for ORTF stereo recording.
The STC 22 uses 21 cm, while the special version (not listed in the catalog) for wide cardioids uses 25 cm.
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