Abstract: The Gome-type Total Ozone Essential Climate Variable (Gto-ecv) Is A Level-3 Data Record, Which Combines Individual Sensor Products Into One Single Cohesive Record Covering The 22-year Period From 1995 To 2016, Generated In The Frame Of The European Space Agency's Climate Change Initiative Phase Ii. It Is Based On Level-2 Total Ozone Data Produced By The Godfit (Gome-type Direct Fitting) V4 Algorithm As Applied To The Gome/ers-2, Omi/aura, Sciamachy/envisat And Gome-2/metop-a And Metop-b Observations. In This Paper We Examine Whether Gto-ecv Meets The Specific Requirements Set By The International Climate–chemistry Modelling Community For Decadal Stability Long-term And Short-term Accuracy. In The Following, We Present The Validation Of The 2017 Release Of The Climate Research Data Package Total Ozone Column (Crdp Toc) At Both Level 2 And Level 3. The Inter-sensor Consistency Of The Individual Level-2 Data Sets Has Mean Differences Generally Within 0.5% At Moderate Latitudes (±50°), Whereas The Level-3 Data Sets Show Mean Differences With Respect To The Omi Reference Data Record That Span Between −0.2±0.9% (For Gome-2b) And 1.0±1.4% (For Sciamachy). Very Similar Findings Are Reported For The Level-2 Validation Against Independent Ground-based Toc Observations Reported By Brewer, Dobson And Saoz Instruments: The Mean Bias Between Godfit V4 Satellite Toc And The Ground Instrument Is Well Within 1.0±1.0% For All Sensors, The Drift Per Decade Spans Between −0.5% And 1.0±1.0% Depending On The Sensor, And The Peak-to-peak Seasonality Of The Differences Ranges From ∼ 1% For Gome And Omi To ∼ 2% For Sciamachy. For The Level-3 Validation, Our First Goal Was To Show That The Level-3 Crdp Produces Findings Consistent With The Level-2 Individual Sensor Comparisons. We Show A Very Good Agreement With 0.5 To 2% Peak-to-peak Amplitude For The Monthly Mean Difference Time Series And A Negligible Drift Per Decade Of The Differences In The Northern Hemisphere Of −0.11±0.10%decade−1 For Dobson And +0.22±0.08%decade−1 For Brewer Collocations. The Exceptional Quality Of The Level-3 Gto-ecv V3 Toc Record Temporal Stability Satisfies Well The Requirements For The Total Ozone Measurement Decadal Stability Of 1–3% And The Short-term And Long-term Accuracy Requirements Of 2 And 3%, Respectively, Showing A Remarkable Inter-sensor Consistency, Both In The Level-2 Godfit V4 And In The Level-3 Gto-ecv V3 Datasets, And Thus Can Be Used For Longer-term Analysis Of The Ozone Layer, Such As Decadal Trend Studies, Chemistry–climate Model Evaluation And Data Assimilation Applications.