It is well established that a property settlement agreement is a contract between the parties and that their rights and obligations are defined under it. See Douglas v. Hammett, 28 Va. App. 517, 523, 507 S.E.2d 98, 101 (1998) (separation agreements and property settlement agreements are contracts); Jones v. Jones, 19 Va. App. 265, 268-69, 450 S.E.2d 762, 764 (1994) ("We must apply the same rules of interpretation to property settlement agreements as are applicable to contracts generally."); Tiffany v. Tiffany, 1 Va. App. 11, 15, 332 S.E.2d 796, 799 (1985). "Where a contract is complete on its face, is plain and unambiguous in its terms, the court is not at liberty to search for its meaning beyond the instrument itself . . . ." Harris v. Woodrum, 3 Va. App. 428, 432, 350 S.E.2d 667, 669 (1986) (quoting Berry v. Klinger, 225 Va. 201, 208, 300 S.E.2d 792, 796 (1983) (quoting Globe Iron Constr. Co. v. First Nat. Bank of Boston, 205 Va. 841, 848, 140 S.E.2d 629, 633 (1965))). In determining the intent of the parties, courts will generally not infer covenants and promises which are not contained in the written provisions. However, What is necessarily implied is as much a part of the instrument as if plainly expressed, and will be enforced as such. If the language of the instrument leaves the meaning of the parties in doubt, the court will take into consideration the occasion which gave rise to it, the obvious design of the parties, and the object to be attained, as well as the language of the instrument itself, and give effect to that construction which will effectuate the real intent and meaning of the parties. Va. Ry. & Power Co. v. City of Richmond, 129 Va. 592, 611, 106 S.E. 529, 536 (1921) (citing Southern Ry. Co. v. Franklin Co., 96 Va. 693, 32 S.E. 485 (1899)). In determining the parties' intent, courts are never shut out from the same light which the parties enjoyed when the contract was executed, and in that view they are entitled to place themselves in the same situation which the parties who made the contract occupied, so as to view the circumstances as they viewed them and so to judge of the meaning of the words and of the correct application of the language to the things described. Talbott v. Richmond & Danville R. R. Co., 72 Va. (31 Gratt) 685 (1879); see also Paul v. Paul, 214 Va. 651, 653, 203 S.E.2d 123, 125 (1974) ("Ascertainment of the intent of the contracting parties is the cardinal rule in the construction of agreements. To do that the court will put itself in the situation occupied by the parties and look to the language employed, the subject matter and purpose of the parties, and all other pertinent circumstances.").