Specify network architecture in Tesseract 4

[Soumik Ranjan Dasgupta]

I'm trying to create a custom network for training tesseract 4 with the following architecture :

784 - 15 -10 [ 3 fully connected layers ]

I ran this command 

 lstmtraining --debug_interval 0   --traineddata ./digits/digits.traineddata   --net_spec '[1,28,28,1 Fs15 O1s10]'   --model_output ~/tesstutorial/o/base --learning_rate 20e-4   --train_listfile ./digits.training_files.txt --max_iterations 5000 &>~/tesstutorial/o/basetrain.log

and this is the output :

 

Invalid F spec!:s15 O1s10]
Missing ] at end of [Series]!
Failed to create network from spec: [1,28,28,1 Fs15 O1s10]

What am I doing wrong? Input images are scaled to 28 x 28 pixels.