There are two types of errors in chaining –

Compensating error:

•  These are caused by incorrect holding and marking of arrow, incorrect plumbing at slopes etc.

•  These errors are proportional to square root of the length of a line

•  They do not affect result much

•  They can't be corrected.

Cumulative error:

•  These errors are liable to occur in same direction and tend to accumulate e.g. error due to sag, slope etc.

•  These errors are proportional to length of line.

•  They can be corrected.