In suits authorized by Section 17.005, Civil Practice and Remedies Code, plaintiff, his agent or attorney shall make and file with the clerk of the court an affidavit, stating
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(a) the name of the grantee as set out in the conveyance constituting source of title of defendants, and
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(b) stating that affiant does not know the names of any persons claiming title or interest under such conveyance other than as stated in plaintiff's petition and
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(c) if the conveyance is to a company or association name as grantee, further stating whether grantee is incorporated or unincorporated, if such fact is known, and if such fact is unknown, so stating.
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Said clerk shall thereupon issue a citation for service upon all persons claiming any title or interest in such land under such conveyance. The citation in such cases shall contain the requisites and be served in the manner provided in Rules 114, 115 and 116.