Procedure for measuring a level of a medium in a vessel with a level transmitter that operates according to the transit time principle which, in the measuring mode, sends transmission signals in the direction of the medium into the vessel and, on the basis of the signal components reflected back in the vessel, derives echo functions (A(t)) that reproduce the amplitudes of the signal components as a function of their transit time (t), with the aid of a table, - whose lines correspond to discrete levels and whose columns correspond to discrete transit times (t), and - in which information, derived from echo functions (A(t)) derived in the past, concerning transit times (t) of maxima of echo functions which are attributable to reflections at reflectors located in the vessel is recorded as historical measuring points in the specific line whose line index corresponds to the associated fill level, characterized in that - the table is updated continuously on the basis of current echo functions (A(t)) derived during measurement, -- wherein information, derived from current echo functions (A(t)), about transit times (t) of maxima of echo functions which are attributable to reflections at reflectors located in the vessel, is recorded as current measuring points in the line whose line index corresponds to the associated level determined by the level transmitter, -- wherein a plausibility check is performed on the basis of the historical and current measuring points by determining at least one regression line segment (GB, GS1, GS2), using appropriately selected current and historical measuring points which are saved in the table, which reflects the dependence of transit times t - which are to be assigned to the same reflector which is different from the surface of the medium - in relation to the fill level L, wherein the plausibility is checked on the basis of the scatter σ of the current and historical measuring points used to determine the at least one regression line segment (GB, GS1, GS2) and/or the slope (ΔL/Δt) of the at least one regression line segment (GB, GS1, GS2), and -- on the basis of the plausibility check, historical and current measuring points which are found to be implausible are deleted and all other current measuring points are transferred to the table as historical measuring points - whose lines correspond to discrete levels and whose columns correspond to discrete transit times (t), and - in which information, derived from echo functions (A(t)) derived in the past, concerning transit times (t) of maxima of echo functions which are attributable to reflections at reflectors located in the vessel is recorded as historical measuring points in the specific line whose line index corresponds to the associated fill level, characterized in that - the table is updated continuously on the basis of current echo functions (A(t)) derived during measurement, -- wherein information, derived from current echo functions (A(t)), about transit times (t) of maxima of echo functions which are attributable to reflections at reflectors located in the vessel, is recorded as current measuring points in the line whose line index corresponds to the associated level determined by the level transmitter, -- wherein a plausibility check is performed on the basis of the historical and current measuring points by determining at least one regression line segment (GB, GS1, GS2), using appropriately selected current and historical measuring points which are saved in the table, which reflects the dependence of transit times t - which are to be assigned to the same reflector which is different from the surface of the medium - in relation to the fill level L, wherein the plausibility is checked on the basis of the scatter σ of the current and historical measuring points used to determine the at least one regression line segment (GB, GS1, GS2) and/or the slope (ΔL/Δt) of the at least one regression line segment (GB, GS1, GS2), and -- on the basis of the plausibility check, historical and current measuring points which are found to be implausible are deleted and all other current measuring points are transferred to the table as historical measuring points -- wherein information, derived from current echo functions (A(t)), about transit times (t) of maxima of echo functions which are attributable to reflections at reflectors located in the vessel, is recorded as current measuring points in the line whose line index corresponds to the associated level determined by the level transmitter, -- wherein a plausibility check is performed on the basis of the historical and current measuring points by determining at least one regression line segment (GB, GS1, GS2), using appropriately selected current and historical measuring points which are saved in the table, which reflects the dependence of transit times t - which are to be assigned to the same reflector which is different from the surface of the medium - in relation to the fill level L, wherein the plausibility is checked on the basis of the scatter σ of the current and historical measuring points used to determine the at least one regression line segment (GB, GS1, GS2) and/or the slope (ΔL/Δt) of the at least one regression line segment (GB, GS1, GS2), and -- on the basis of the plausibility check, historical and current measuring points which are found to be implausible are deleted and all other current measuring points are transferred to the table as historical measuring points