Sorry I missed this post previously. Are you looking to update the actual file contents or just the metadata about the file (such as description)? I'm assuming you're looking to update the actual file. Maximo doesn't support updating an attachment (even from the UI) so there's not a process to "update" an attachment through the integration framework. You'd have to delete and add in the attachment as if it was a new file from the API.
If you're hosting attachments external to Maximo (IE SharePoint) you could update them in that system. For those that want to perform updates to the file that's what I'd recommend so you ensure you have accurate version history.
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Steven Shull
IBM
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