SDE.ST_M() returns negative infinity

[Bud]

ArcMap & Enterprise 10.7.1 — Oracle 18c SDE.ST_GEOMETRY — SQL Developer 18:

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I have an SDE.ST_GEOMETRY polyline FC that is M-enabled:

In an SQL client like SQL Developer, I can query for the M-value of the endpoint of the line:

select
    sde.st_m(sde.st_endpoint(shape))
from
    my_fc

The result of that query is -Infinity.  I didn't know that was possible and I wouldn't have thought to account for it when querying for possible values.

Question:

Is that behavior expected from ST_GEOMETRY functions? If anything, I would have expected the value to be Null, not -Infinity.