[R-sig-ME] Don't understand this variance components output

[Stuart Luppescu]

Hello, I'm analyzing ratings of teacher performance on 9 components.
Each teacher is rated between 1 and 6 times. The average number of
ratings per teacher is about 3.5. The structure of the data is (teachers
nested within observations) crossed by components. The lmer call is:
 
lme6 <- lmer(rating ~ (1|tid.f) +  (1|comp.f) + (1|tid.f/obsorder.f),
data=ratings, REML=FALSE)

The outcome is rating; tid.f is the teacher ID; comp.f is the component
ID; obsorder.f is the observation. Here is the summary output:

Random effects:
 Groups           Name        Variance Std.Dev.
 obsorder.f.tid.f (Intercept) 0.06574  0.2564  
 tid.f            (Intercept) 0.16309  0.4038  
 tid.f.1          (Intercept) 0.03498  0.1870  
 comp.f           (Intercept) 0.01589  0.1261  
 Residual                     0.19696  0.4438  
Number of obs: 166405, groups: obsorder.f:tid.f, 18496; tid.f, 5486;
comp.f, 9

Fixed effects:
            Estimate Std. Error t value
(Intercept)  2.82680    0.04252   66.49

What I don't get is the line in the list of random effects labeled
tid.f.1. What is this? Am I not specifying the model correctly?

Here is my sessionInfo:
R version 3.0.2 (2013-09-25)
Platform: x86_64-redhat-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_US       LC_NUMERIC=C         LC_TIME=en_US       
 [4] LC_COLLATE=en_US     LC_MONETARY=en_US    LC_MESSAGES=en_US   
 [7] LC_PAPER=en_US       LC_NAME=C            LC_ADDRESS=C        
[10] LC_TELEPHONE=C       LC_MEASUREMENT=en_US LC_IDENTIFICATION=C 

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods
base     

other attached packages:
 [1] plyr_1.8        reshape2_1.2.2  MCMCglmm_2.17   corpcor_1.6.6  
 [5] ape_3.0-11      coda_0.16-1     tensorA_0.36    MASS_7.3-29    
 [9] foreign_0.8-59  lme4_1.0-5      Matrix_1.1-1.1  lattice_0.20-24

loaded via a namespace (and not attached):
[1] compiler_3.0.2 grid_3.0.2     minqa_1.2.2    nlme_3.1-113
splines_3.0.2 
[6] stringr_0.6.2  tools_3.0.2   

Thanks very much for the help.

-- 
Stuart Luppescu <slu at ccsr.uchicago.edu>