The 67 dB rule applies to any TIA Perm. Link test limit containing the ACR-F measurement.
If at any frequency the FEXT is less than 67 dB, the ACR-F cannot fail at that frequency.
ACR-F is a calculation of FEXT minus the Insertion Loss.
On VERY RARE occasions, you may see "i" against the ACR-F summary result, meaning that the entire FEXT measurement was less than 67 dB for all pair combinations, so all of the ACR-F calculations are "ignored" or as the standards phrase it; "for information only".
This "i" will ressult in N/A appearing in the LinkWare Software and is nothing to be concerned about.
This was added in Version 2,74 Software.
Practically speaking, it will not turn an existing FAIL into a PASS or vice versa.
