WA allowable evidence for trial

[SP3]

In a dividing fences dispute which is heading for trial, what evidence is permissable? For example. Is an email from a building surveyor saying the fence is a "sufficient" fence OK to present to the court without the building surveyor appearing as a witness?
Is a signed statement from a tenant OK to use as evidence without the tenant being a witness?
Is an excerpt from the Government dividing fences guide OK as evidence?

 

[Tim W]

Two ways to answer this.

Yes, documents can be acceptable.
No, the people can't always and automatically escape being summonsed
by providing a document instead.
If you want, or need, them to appear, they can be made to.

 

[SP3]

Two ways to answer this.

Yes, documents can be acceptable.
No, the people can't always and automatically escape being summonsed
by providing a document instead.
If you want, or need, them to appear, they can be made to.

OK, Thanks for your response.