I cannot imagine you would need to file one if you did not actually participate in the collaborative divorce process. It may have just been an option to check off on the form if you did indeed do a collaborative action.
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If you don't already know what that is, it doesn't alloy to you. It's an option that throws the whole procedural stance of the case into a different schedule and everything, but it's not commonly used, and for that matter I really don't see how you could even do it without attorneys being involved. I think you either have the wrong form, or you've got some kind of all-inclusive form that just covers that as an option.
If you are not represented by an attorney and are writing your own divorce decree, I suggest you hire an attorney to look it over to make sure you are not including provisions that are irrelevant to your situation.
The Collaborative family law process is defined in the Texas Family Code as "a procedure intended to resolve a collaborative family law matter without intervention by a tribunal in which parties (A) sign a collaborative family law participation agreement; and (B) are represented by collaborative family law lawyers." Section 15.052(4) Tex. Fam. Code. The collaborative Family Law Participation Agreement itself is a contract between the parties containing certain required provisions (Section 15.101 Texas Family Code). In general it just states the parties intent to follow collaborative law procedures with respect to their family law matter, identifies each parties' attorney, and sets forth the ground rules for the process.
If you are writing your own divorce decree, I assume that you are not represented by an attorney and have not been involved in resolving your divorce through the collaborative law process. If that is the case, you do not need to sign one and the language your referenced is irrelevant.
Even if you are participating in the collaborative law process, the actual Collaborative Law Participation Agreement need not be filed with Court. Instead, the parties file a Notice of the agreement which lets the Court know to stay the proceedings (subject to certain exceptions) to allow the collaborative process to take place. But again, you and your spouse would have to be represented by collaborative law lawyers who would take care of that for you.
This answer is not intended as legal advice, does not establish a attorney-client relationship, and assumes that Texas law applies to your question.