What exactly does "restricted to versions 1.0.0 by an explicit requirement" mean?

I am struggling to parse those Pkg “Unsatisfiable requirements” errors (see example below). In particular, what does “restricted to versions 1.0.0 by an explicit requirement” mean exactly? More precisely, where is it explicit?

ERROR: Unsatisfiable requirements detected for package TableTraits [3783bdb8]:
 TableTraits [3783bdb8] log:
 ├─possible versions are: [0.0.1-0.0.3, 0.1.0, 0.2.0, 0.3.0-0.3.1, 0.4.0-0.4.1, 1.0.0] or uninstalled
 ├─restricted to versions * by Tables [bd369af6], leaving only versions [0.0.1-0.0.3, 0.1.0, 0.2.0, 0.3.0-0.3.1, 0.4.0-0.4.1, 1.0.0]
 │ └─Tables [bd369af6] log:
 │   ├─possible versions are: 0.2.0 or uninstalled
 │   └─Tables [bd369af6] is fixed to version 0.2.0
 ├─restricted to versions 1.0.0 by an explicit requirement, leaving only versions 1.0.0
 └─restricted by compatibility requirements with QueryOperators [2aef5ad7] to versions: [0.0.1-0.0.3, 0.1.0, 0.2.0, 0.3.0-0.3.1, 0.4.0-0.4.1] — no versions left
   └─QueryOperators [2aef5ad7] log:
     ├─possible versions are: [0.0.1-0.0.2, 0.1.0-0.1.1, 0.2.0-0.2.3, 0.3.0, 0.4.0, 0.5.0-0.5.2, 0.6.0, 0.7.0-0.7.1, 0.8.0] or uninstalled
     ├─restricted to versions * by an explicit requirement, leaving only versions [0.0.1-0.0.2, 0.1.0-0.1.1, 0.2.0-0.2.3, 0.3.0, 0.4.0, 0.5.0-0.5.2, 0.6.0, 0.7.0-0.7.1, 0.8.0]
     └─restricted by compatibility requirements with IteratorInterfaceExtensions [82899510] to versions: 0.0.1 or uninstalled, leaving only versions: 0.0.1
       └─IteratorInterfaceExtensions [82899510] log:
         ├─possible versions are: [0.0.1-0.0.2, 0.1.0-0.1.1, 1.0.0] or uninstalled
         ├─restricted to versions * by Tables [bd369af6], leaving only versions [0.0.1-0.0.2, 0.1.0-0.1.1, 1.0.0]
         │ └─Tables [bd369af6] log: see above
         └─restricted to versions 1.0.0 by an explicit requirement, leaving only versions 1.0.0

There’s another example here
with an explanation in this post

maybe this?