EXFO MaxTester 635 - Manual (Page 311)

Running DSL/IP Tests and Viewing Results
Copper and VDSL2/ADSL2+ Multi-play Test Set 303
DSL Statistics

Vector Err. Samples Sent is the total number of error samples the CPE
has sent to the DSLAM during the test. A high number can indicate a
network that is unstable (CPEs joining / leaving, causing the VCE to
continuously recalculate the best solution).

Vector Err. Samples Dis. is the total number of error samples
discarded. A high number can indicate a network that is unstable
(CPEs joining / leaving, causing the VCE to continuously recalculate the
best solution).