As a general rule, avoid direct formatting because its formatting “directives” are sticky and override all other.
If you have no direct formatting, only the paragraph and character style names are pasted. As a consequence, formatting will be as defined by current document styles. Of course if the styles do not exist, their definitions in the source document are added to the current document so that nothing is left dangling.
The above behaviour is valid for Writer-Writer copy & paste. In “foreign” environment, i.e. other-Writer copy & paste, the situation depends on import filters. For totally unknown sources, you have unformatted text paste. But for somehow managed sources, you end up with direct formatting.
HTML case: as Writer has a web page generation capability (WriterWeb), it understands HTML formatting (and CSS) and converts it to direct formatting. You then need unformatted text paste or clear direct formatting (
M$ Word case: similar to previous case; I have not experimented to see if Word paragraph style (its only style category) is forwarded without direct formatting but any other decoration ends up with single-usage character styles which pollute and overload the style dictionary. Here clear direct formatting will not always fix the situation. Paste unformatted is required to avoid any original formatting.
Experiment of see the degree of formatting import with other filters.
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