Blue Veil

In the gel image, appears as a blue haze migrating downward like a veil

Dye Blobs

Bright fluorescence superimposed on sequence, caused by the inefficient removal of unincorporated dye terminators post-PCR.
Observed in both the gel image and the trace file view as large wide peaks.

G-Stop

In the trace file view, observed as an abrupt termination of signal following a run of Gís.

Mobility Error

Wrong mobility file applied, causing base peaks to appear shifted particularly at the start of the sequence.

Multiple Priming Sites

Observed as multiple sequences/peaks superimposed, often due to extension products being generated from multiple priming sites

Red Rain

From the gel image, appears as red streaks migrating down from the top of the screen

Slippage

Polymerase slippage during PCR amplification and/or cycle sequencing due to a homopolymeric region in the template. Electropherogram may show a stutter or sawtooth pattern

Spike

Large sharp peaks in data, may be one-color or four-color.

Trailing Signal

Signal intensity decreases, appearing as gradually decreasing peak heights

Waterfall

This refers to the raw data baseline.  A raised baseline in all colors is observed at the start, which then drops after a given amount of time in a waterfall pattern.  There may be a signal dropout visible in the electropherogram at this point.