Getting trust information for UIDs

[Patrick Brunschwig]

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When sending an encrypted mail I want to display in a list the
keys/UID's and their trust level. For this I use
gpg --with-colons --list-keys

Now, I have the following problem. If a secondary UID is not signed, in
the calc. trust field there is a "-", indicating that this UID is not
trusted. However, if a secondary UID is signed but the primary UID is
not signed, the calc. trust can be "f" but still the UID is not trusted.

Is it correct that I have no way using --with-colons --list-keys to find
 out the trust level of primary UIDs? If so, is there any other way to
get the calculated trust of UIDs correctly without needing to check all
signatures?

- -Patrick
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