The soft selection rollup is identical to Edit Mesh, with two exceptions:
With "Affect hidden vertices" you can determine if currently hidden vertices should be affected or not.
And There's a "lock" switch, where you can lock the current soft selection:
With default soft selection, you lose the current soft selection each time you move a vertex:
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| before moving vertex | while moving vertex | after moving vertex - the soft selection is lost and now refers to the new vertex position |
With locked soft selection, you can do many moves with the same soft selection:
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| before moving vertex | while moving vertex | after moving vertex - the soft selection is kept! |