diff --git a/km3io/definitions/events.csv b/km3io/definitions/events.csv
new file mode 100644
index 0000000000000000000000000000000000000000..70bab22fd31b854dbac29f1c0b0ec0cb76c8ff6b
--- /dev/null
+++ b/km3io/definitions/events.csv
@@ -0,0 +1,23 @@
+#type,name,comment
+
+int,id,offline event identifier
+int,det_id,detector identifier from DAQ
+int,mc_id,identifier of the MC event (as found in ascii or antcc file)
+int,run_id,DAQ run identifier
+int,mc_run_id,MC run identifier
+int,frame_index,from the raw data
+ULong64_t,trigger_mask,trigger mask from raw data (i.e. the trigger bits)
+ULong64_t,trigger_counter,trigger counter
+unsigned int,overlays,number of overlaying triggered events
+TTimeStamp,t,UTC time of the start of the timeslice the event came from
+vec Hit,hits,list of hits
+vec Trk,trks,list of reconstructed tracks (can be several because of prefits,showers, etc)
+vec double,w,MC: Weights w[0]=w1 & w[1]=w2 &  w[2]]=w3
+vec double,w2list,MC: factors that make up w[1]=w2
+vec double,w3list,MC: atmospheric flux information
+double,mc_t,MC: time of the mc event
+vec Hit,mc_hits,MC: list of MC truth hits
+vec Trk,mc_trks,MC: list of MC truth tracks
+string,comment,user can use this as he/she likes
+int,index,user can use this as he/she likes
+int,flags,user can use this as he/she likes
diff --git a/km3io/definitions/hits.csv b/km3io/definitions/hits.csv
new file mode 100644
index 0000000000000000000000000000000000000000..54114ba58288cf1612e4f579e1e742ca0cf7e706
--- /dev/null
+++ b/km3io/definitions/hits.csv
@@ -0,0 +1,19 @@
+#type,name,comment
+
+int,id,hit id
+int,dom_id,module identifier from the data (unique in the detector)
+unsigned int,channel_id,PMT channel id {0,1, .., 31} local to module
+unsigned int,tdc,hit tdc (=time in ns)
+unsigned int,tot,tot value as stored in raw data (int for pyroot)
+int,trig,non-zero if the hit is a trigger hit
+int,pmt_id,global PMT identifier as found in evt files
+double,t,hit time (from calibration or MC truth)
+double,a,hit amplitude (in p.e.)
+vec,pos,hit position
+vec,dir,hit direction i.e. direction of the PMT
+double,pure_t,photon time before pmt simultion (MC only)
+double,pure_a,amptitude before pmt simution (MC only)
+int,type,particle type or parametrisation used for hit (mc only)
+int,origin,track id of the track that created this hit
+unsigned,pattern_flags,some number that you can use to flag the hit
+
diff --git a/km3io/definitions/offlinehead.csv b/km3io/definitions/offlinehead.csv
new file mode 100644
index 0000000000000000000000000000000000000000..dffd5e5856459ac7125a03b17cbeaf07c901ca0e
--- /dev/null
+++ b/km3io/definitions/offlinehead.csv
@@ -0,0 +1,22 @@
+#name,comment
+
+DAQ,livetime
+cut_primary cut_seamuon cut_in cut_nu,Emin Emax cosTmin cosTmax
+generator physics simul,program version date time
+seed,program level iseed
+PM1_type_area,type area TTS
+PDF,i1 i2
+model,interaction muon scattering numberOfEnergyBins
+can,zmin zmax r
+genvol,zmin zmax r volume numberOfEvents
+merge,time gain
+coord_origin,x y z
+translate,x y z
+genhencut,gDir Emin
+k40,rate time
+norma,primaryFlux numberOfPrimaries
+livetime,numberOfSeconds errorOfSeconds
+flux,type key file_1 file_2
+spectrum,alpha
+fixedcan,xcenter ycenter zmin zmax radius
+start_run,run_id
diff --git a/km3io/definitions/tracks.csv b/km3io/definitions/tracks.csv
new file mode 100644
index 0000000000000000000000000000000000000000..5a914b219c1b7ec3c4520f1fa3c4bad4d35b90b3
--- /dev/null
+++ b/km3io/definitions/tracks.csv
@@ -0,0 +1,18 @@
+#type,name,comment
+
+int,id,track identifier
+vec,pos,position of the track at time t
+vec,dir,track direction
+double,t,track time (when particle is at pos)
+double,E,Energy (either MC truth or reconstructed)
+double,len,length if applicable
+double,lik,likelihood or lambda value (for aafit: lambda)
+int,type,MC: particle type in PDG encoding
+int,rec_type,identifyer for the overall fitting algorithm/chain/strategy
+vec int,rec_stages,list of identifyers of succesfull fitting stages resulting in this track
+int,status,MC status code
+int,mother_id,MC id of the parent particle
+vec double,fitinf,place to store additional fit info for jgandalf see FitParameters.csv
+vec int, hit_ids,list of associated hit-ids (corresponds to Hit::id)
+vec double,error_matrix,(5x5) error covariance matrix (stored as linear vector)
+string,comment,user comment