Hi Nashrazo:
In my layman understanding, more or less in tax declarations or in land titles or in general use of this term "more or less", ibig sabihin "maaaring humigit o kumulang" sa nasabing "figure" i.e.... 120 sqms. area, more or less, ay maaaring kulang sa 120 or higit sa 120. Purpose of tax declaration ay ginagamit ng assessor's office to determine how much realty tax is due on that assessed property, and it is not a legal document of ownership of the property but is only for realty tax payment purposes. Limitations? what do you mean by this? Tax declarations copy cannot be given to anyone who wants a copy, and to limit its distribution, you can write to the assessor's office that without your written permission, no copies of your tax declaration be given or pass on to anyone. If you mean "limitations as to the assessment value", I think the assessor's office has their own guideline, sometimes a little bit lower from the BIR Zonal value on the land as to its location, class, size, etc., but on improvements I think the assessor's office based their assessment on the current value of the structure/improvement. Actually, the tax payer is the one declaring the cost of acquisition of the property to the assessor's office.
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I am not a lawyer neither a surveyor nor an engineer, I am only sharing my little understanding and knowledge on what you posted.